Lawsonia intracellularis infection and proliferative enteropathy in foals.

Equine proliferative enteropathy (EPE) is a disease of foals caused by the obligate intracellular organism Lawsonia intracellularis. This organism is unique in that it causes proliferation of infected enterocytes, resulting in thickening of the intestinal epithelium, most often the small intestine. This disease affects mainly weanling foals and causes fever, lethargy, peripheral edema, diarrhea, colic and weight loss. The diagnosis of EPE may be challenging and relies on the presence of hypoproteinemia, thickening of segments of the small intestinal wall observed on abdominal ultrasonography, positive serology and molecular detection of L. intracellularis in feces. The epidemiology and genetic basis for pathogenesis for this disease is beginning to be elucidated. Phenotypic traits, genomic features, and gene expression profiles during L. intracellularis infection in vitro and in vivo are presented. In addition, this article reviews the epidemiology, pathological and clinicopathological findings, diagnosis, and control of EPE

Establishment of porcine enterocyte/myofibroblast co-cultures for the growth of porcine rota- and coronaviruses

A stable culture of primary porcine enterocytes is necessary to study porcine enteric virus replication characteristics. Because the direct cultivation of primary porcine enterocytes is difficult, alternatives have to be considered. As subepithelial myofibroblasts secrete extracellular matrix and growth factors contributing to the attachment, proliferation and differentiation of epithelial cells, co-cultures of primary porcine enterocytes (ileocytes and colonocytes) with myofibroblasts were developed and evaluated for their susceptibility to enteric viruses. First, it was demonstrated that the co-cultured ileocytes and colonocytes were susceptible to an archival rotavirus strain RVA/pig-tc/BEL/RV277/1977/ G1P[7] and different other rotavirus genotypes (fecal samples containing G5P[7], G5P[13], G9P[23], G4P[6]). Next, the TGEV Purdue strain infected both ileocytes and colonocytes whereas the Miller strain only infected ileocytes. Last, the PEDV CV777 Vero adapted and non-adapted (fecal suspension) strains could infect co-cultured ileocytes but not colonocytes. The infectivity of the CV777 Vero adapted strain was higher when the cells were cultured without fetal bovine serum and the CV777 fecal suspension only infected the ileocytes cultured without fetal bovine serum. In conclusion, a novel co-culture of porcine enterocytes with myofibroblasts was established, which can be used for the investigation of the replication of enteric viruses

Equine proliferative enteropathy--a review of recent developments.

Equine proliferative enteropathy (EPE) is a disease of foals caused by the obligate intracellular organism Lawsonia intracellularis. This emerging disease affects mainly weanling foals and causes fever, lethargy, peripheral oedema, diarrhoea, colic and weight loss. The diagnosis of EPE may be challenging and relies on the presence of hypoproteinaemia, thickening of segments of the small intestinal wall observed upon abdominal ultrasonography, positive serology and molecular detection of L. intracellularis in faeces. Although the clinical entity, diagnostic approach and treatment of EPE are well established and described, the epidemiology for this disease has remained largely unaddressed. This article focuses on new developments in the field of EPE, including epidemiology, pathophysiology, clinical signs, diagnosis, treatment and prevention

Role of Porcine Aminopeptidase N and Sialic Acids in Porcine Coronavirus Infections in Primary Porcine Enterocytes.

Porcine epidemic diarrhea virus (PEDV) and transmissible gastroenteritis virus (TGEV) have been reported to use aminopeptidase N (APN) as a cellular receptor. Recently, the role of APN as a receptor for PEDV has been questioned. In our study, the role of APN in PEDV and TGEV infections was studied in primary porcine enterocytes. After seven days of cultivation, 89% of enterocytes presented microvilli and showed a two- to five-fold higher susceptibility to PEDV and TGEV. A significant increase of PEDV and TGEV infection was correlated with a higher expression of APN, which was indicative that APN plays an important role in porcine coronavirus infections. However, PEDV and TGEV infected both APN positive and negative enterocytes. PEDV and TGEV Miller showed a higher infectivity in APN positive cells than in APN negative cells. In contrast, TGEV Purdue replicated better in APN negative cells. These results show that an additional receptor exists, different from APN for porcine coronaviruses. Subsequently, treatment of enterocytes with neuraminidase (NA) had no effect on infection efficiency of TGEV, implying that terminal cellular sialic acids (SAs) are no receptor determinants for TGEV. Treatment of TGEV with NA significantly enhanced the infection which shows that TGEV is masked by SAs

Role of porcine amino peptidase N and sialic acids in porcine coronavirus infections in primary porcine enterocytes

Porcine epidemic diarrhea virus (PEDV) and transmissible gastroenteritis virus (TGEV) have been reported to use aminopeptidase N (APN) as a cellular receptor. Recently, the role of APN as a receptor for PEDV has been questioned. In our study, the role of APN in PEDV and TGEV infections was studied in primary porcine enterocytes. After seven days of cultivation, 89% of enterocytes presented microvilli and showed a two- to five-fold higher susceptibility to PEDV and TGEV. A significant increase of PEDV and TGEV infection was correlated with a higher expression of APN, which was indicative that APN plays an important role in porcine coronavirus infections. However, PEDV and TGEV infected both APN positive and negative enterocytes. PEDV and TGEV Miller showed a higher infectivity in APN positive cells than in APN negative cells. In contrast, TGEV Purdue replicated better in APN negative cells. These results show that an additional receptor exists, different from APN for porcine coronaviruses. Subsequently, treatment of enterocytes with neuraminidase (NA) had no effect on infection efficiency of TGEV, implying that terminal cellular sialic acids (SAs) are no receptor determinants for TGEV. Treatment of TGEV with NA significantly enhanced the infection which shows that TGEV is masked by SAs

A Guide to Human Zinc Absorption: General Overview and Recent Advances of In Vitro Intestinal Models

Zinc absorption in the small intestine is one of the main mechanisms regulating the systemic homeostasis of this essential trace element. This review summarizes the key aspects of human zinc homeostasis and distribution. In particular, current knowledge on human intestinal zinc absorption and the influence of diet-derived factors on bioaccessibility and bioavailability as well as intrinsic luminal and basolateral factors with an impact on zinc uptake are discussed. Their investigation is increasingly performed using in vitro cellular intestinal models, which are continually being refined and keep gaining importance for studying zinc uptake and transport via the human intestinal epithelium. The vast majority of these models is based on the human intestinal cell line Caco-2 in combination with other relevant components of the intestinal epithelium, such as mucin-secreting goblet cells and in vitro digestion models, and applying improved compositions of apical and basolateral media to mimic the in vivo situation as closely as possible. Particular emphasis is placed on summarizing previous applications as well as key results of these models, comparing their results to data obtained in humans, and discussing their advantages and limitations.DFG, 316442145, FOR 2558: Interaktionen von essenziellen Spurenelementen in gesunden und erkrankten älteren Menschen (TraceAge)DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berli

The Regulatory Role of MeAIB in Protein Metabolism and the mTOR Signaling Pathway in Porcine Enterocytes.

Amino acid transporters play an important role in cell growth and metabolism. MeAIB, a transporter-selective substrate, often represses the adaptive regulation of sodium-coupled neutral amino acid transporter 2 (SNAT2), which may act as a receptor and regulate cellular amino acid contents, therefore modulating cellular downstream signaling. The aim of this study was to investigate the effects of MeAIB to SNAT2 on cell proliferation, protein turnover, and the mammalian target of rapamycin (mTOR) signaling pathway in porcine enterocytes. Intestinal porcine epithelial cells (IPEC)-J2 cells were cultured in a high-glucose Dulbecco's modified Eagle's (DMEM-H) medium with 0 or 5 mmoL/L System A amino acid analogue (MeAIB) for 48 h. Cells were collected for analysis of proliferation, cell cycle, protein synthesis and degradation, intracellular free amino acids, and the expression of key genes involved in the mTOR signaling pathway. The results showed that SNAT2 inhibition by MeAIB depleted intracellular concentrations of not only SNAT2 amino acid substrates but also of indispensable amino acids (methionine and leucine), and suppressed cell proliferation and impaired protein synthesis. MeAIB inhibited mTOR phosphorylation, which might be involved in three translation regulators, EIF4EBP1, IGFBP3, and DDIT4 from PCR array analysis of the 84 genes related to the mTOR signaling pathway. These results suggest that SNAT2 inhibition treated with MeAIB plays an important role in regulating protein synthesis and mTOR signaling, and provide some information to further clarify its roles in the absorption of amino acids and signal transduction in the porcine small intestine

Enteric diseases in pigs from weaning to slaughter

The general aim of this thesis was to study enteric diseases in growing pigs, with special reference to diseases caused by Brachyspira hyodysenteriae and Lawsonia intracellularis. The occurrence of enteric diseases in “growers” is a problem of increasing importance in Sweden and an understanding of the mechanisms by which the microorganisms causes enteric diseases is essential to develop good prophylactic measures. The most important microorganisms involved in enteric diseases in grower pigs were identified as Lawsonia intracellularis and Brachyspira pilosicoli, as determined by necropsy, microbiological and histopathological examinations performed on representative growing pigs from good and poor performing herds. Diagnostic methods based on polymerase chain reaction for L. intracellularis in tissue or faecal samples were established and the results related to those obtained by necropsy and serology. An internal control, a mimic, was constructed to demonstrate inhibition of the PCR reactions and to evaluate different preparation methods. The methods for the demonstration of L. intracellularis in tissue samples were sensitive and specific, and the bacteria were reliably identified in faeces from pigs with overt disease. A number of factors interacting in the clinical expression of swine dysentery were evaluated. In this work, group-housing of pigs and the addition of 50% soybean meal in feed was shown to predispose for infection. A model was developed that enabled the sequential monitoring of disease in single animals by repeated endoscopy and biopsy sampling through a caecal cannula. This reduced the number of experimental animals required and increased the accuracy of the study. The general condition of the animal was not affected. The model was used to study the development of experimentally induced swine dysentery and the sequential development of lesions was characterised by histopathology and immunohistochemistry. An increase in the acute phase proteins serum amyloid A and haptoglobin and in monocytes was seen when haemorrhagic dysentery occurred

An update on pathogenesis and control of Salmonella infections in pigs

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