A reverse transcription-polymerase chain reaction method to analyze porcine cytokine gene expression

Replication of infectious bronchitis virus (IBV) Delmarva (DMV)/1639 variant in primary and secondary lymphoid organs leads to immunosuppression in chickens

Infectious bronchitis virus (IBV) that primarily causes respiratory infection in chickens, disseminate to multiple body systems leading to pathology, results in economic losses to poultry industry. IBV replicates in the bursa of Fabricius (BF), Harderian gland (HG), cecal tonsils (CT), and spleen. The objective of this study was to investigate the immunosuppressive effect of IBV Delmarva (DMV/1639) variant in chickens. Specific pathogen free chickens were infected with the IBV DMV/1639 variant while maintaining an age-matched uninfected control group. At predetermined time points, subsets of the infected and control chickens were observed for changes in body weights and pathological changes. The histopathological lesions were observed in the CT and BF, with minimal lesions in the thymus and spleen. The mRNA expression of pro-inflammatory mediators suggested immunomodulation by IBV, favoring viral replication. Further studies are warranted to observe the functional impact of the IBV DMV/1639 variant's replication in immune organs.

Porcine reproductive and respiratory syndrome virus reinfection causes the distribution of porcine interleukin-4 in close proximity to B lymphocytes within lymphoid follicles and a reduction in B and T lymphocytes

Interleukin 4 (IL-4) plays a major role in T-lymphocyte development and is thought to be a central regulator as a cofactor in resting B-lymphocyte proliferation. Primary infection with porcine reproductive and respiratory syndrome virus (PRRSV) induces minimal IL-4 production, whereas an IL-4 response occurs in the peripheral blood of piglets reinfected by PRRSV. The locations and interaction partners for the massive volume of IL-4 triggered by PRRSV reinfection remain unclear. This study aimed to investigate the characteristics of IL-4 secretion and location changes in peripheral immune organs induced by PRRSV infection and reinfection. Our results show that PRRSV reinfection induced higher levels of IL-4 mRNA and protein expression in the peripheral immune organs (e.g., lymph node and spleen) and peripheral blood compared with PRRSV primary infection. Importantly, we found that, following PRRSV reinfection, an obvious large-scale migration of IL-4 occurred in the lymph nodes. During PRRSV primary infection, IL-4 was mainly concentrated around the lymphoid follicles and paracortical regions of the lymph node and also located in the marginal area and periarterial lymphatic sheath region of the spleen. During PRRSV reinfection, the now abundant IL-4 gathered into the lymphoid follicles of the lymph node and spleen. Notably, IL-4 changed its location state from scattered and sparse during primary infection to clinging to B lymphocytes in the lymphoid follicles during reinfection. During reinfection, IL-4 was often co-localized with T and B lymphocytes; furthermore, the percentages of several T lymphocyte subsets, N protein-specific antibody levels, and viral load in the peripheral blood or lymph tissues underwent remarkable variation. Another important finding of this study was that the numbers of B lymphocytes and T lymphocytes in the lymphoid nodes were significantly reduced after PRRSV infection or reinfection, presumably due to PRRSV-induced acute bone marrow failure and autophagy in thymic epithelial cells. This study revealed the characteristics of IL-4 migration and distribution in the peripheral lymph organs induced by PRRSV reinfection and provides valuable clues for further exploration of the interactions between IL-4, B lymphocytes, and T lymphocytes during PRRSV infection and reinfection.

Potential of Oral Nanoparticles Containing Cytokines as Intestinal Mucosal Immunostimulants in Pigs: A Pilot Study

Simple Summary

Antibiotics are essential compounds to cope with bacterial infections. However, their inadequate and excessive use has triggered the rapid arising of antimicrobial-resistant bacteria. In this scenario, immunostimulants, which are molecules that boost the immune system, open up a new approach to face this problem, enhancing treatment efficacy and preventing infections by immune system response. Cytokines are central effector molecules of the immune system, and their recombinant production and administration in animals could be an interesting immune modulation strategy. The aim of this study was the development of a highly stable nanoparticle of porcine cytokines to achieve the immunostimulation of intestinal mucosa in piglets. The outcomes of the present study prove this approach is able to stimulate swine intestinal cells and macrophages in vitro and tends to modulate inflammatory responses in vivo, although further studies are required to definitively evaluate their potential in animals.

Abstract

Antimicrobial resistance is a global threat that is worryingly rising in the livestock sector. Among the proposed strategies, immunostimulant development appears an interesting approach to increase animal resilience at critical production points. The use of nanoparticles based on cytokine aggregates, called inclusion bodies (IBs), has been demonstrated as a new source of immunostimulants in aquaculture. Aiming to go a step further, the objective of this study was to produce cytokine nanoparticles using a food-grade microorganism and to test their applicability to stimulate intestinal mucosa in swine. Four cytokines (IL-1β, IL-6, IL-8, and TNF-α) involved in inflammatory response were produced recombinantly in Lactococcus lactis in the form of protein nanoparticles (IBs). They were able to stimulate inflammatory responses in a porcine enterocyte cell line (IPEC-J2) and alveolar macrophages, maintaining high stability at low pH and high temperature. In addition, an in vivo assay was conducted involving 20 piglets housed individually as a preliminary exploration of the potential effects of IL-1β nanoparticles in piglet intestinal mucosa after a 7 d oral administration. The treated animals tended to have greater levels of TNF-α in the blood, indicating that the tested dose of nanoparticles tended to generate an inflammatory response in the animals. Whether this response is sufficient to increase animal resilience needs further evaluation.

Adiponectin Influences FGF2 in the Developing Porcine Corpus Luteum

Luteal angiogenesis is regulated by pro-angiogenic hormones including fibroblast growth factor 2 (FGF2) and angiopoietin 1 (Ang1), which are regulated by the adipokine leptin during development. Another adipokine, adiponectin, exhibits an inverse relationship with leptin and has been identified in the CL. Therefore, it is hypothesized that adiponectin will influence pro-angiogenic hormones in the developing porcine CL. Crossbred sows were randomly allocated to one of two days of the estrous cycle, day 5 (D5; n = 4) or day 7 (D7; n = 5) for CL collection. Tissue was processed for immunohistochemical localization of adiponectin receptor 2 (AdipoR2), gene expression of FGF2, Ang1, leptin, AdipoR2, and cell culture for adiponectin treatment. The expression of AdipoR2 tended (p = 0.09) to be higher in D7 lutea and was more prevalently localized to the cell surface of large and small luteal cells than in D5 tissue. Adiponectin influenced (p ≤ 0.05) FGF2, leptin, and AdipoR2 gene expression relative to the dose and day (D5 or D7). Collectively, the evidence supports the supposition that adiponectin influences angiogenic factors in the developing CL.

Isoquinoline Alkaloids in Sows' Diet Reduce Body Weight Loss during Lactation and Increase IgG in Colostrum

Simple Summary

Plant extracts containing isoquinoline alkaloids (IQ) have been demonstrated to have anti-inflammatory properties. In pigs, IQ supplementation has been shown to downregulate the stress response and improve the digestibility of nutrients. The present experiment was conducted to test the hypothesis that supplementing sows’ diets with IQ during gestation would decrease stress at farrowing and improve colostrum quality, positively affecting the piglets’ health and performance.

Abstract

Isoquinoline alkaloids (IQ) exert beneficial antimicrobial and anti-inflammatory effects in livestock. Therefore, we hypothesized that supplementing sows’ diets with IQ during gestation would decrease farrowing stress, affecting the piglets’ development and performance. Sows were divided into: IQ1, supplemented with IQ from gestation day 80 (G80) to weaning; IQ2, supplemented from gestation day 110 (G110) to weaning, and a non-supplemented (NC) group. Sow body weight (BW), feed intake, back-fat thickness and back-muscle thickness were monitored. Cortisol, glucose and insulin were measured in sows’ blood collected 5 d before, during, and after 7 d farrowing. Protein, fat, IgA and IgG were analyzed in the colostrum and milk. Piglets were monitored for weight and diarrhea score, and for ileum histology and gene expression 5 d post-weaning. IQ-supplemented sows lost less BW during lactation. Glucose and insulin levels were lower in the IQ groups compared to NC-sows 5 d before farrowing and had higher levels of protein and IgG in their colostrum. No other differences were observed in sows, nor in the measured parameters in piglets. In conclusion, IQ supplementation affected sows’ metabolism, reducing body weight loss during lactation. Providing IQ to sows from their entrance into the maternity barn might be sufficient to induce these effects. IQ improved colostrum quality, increasing the protein and IgG content, improving passive immunity for piglets.

AQP3 Facilitates Proliferation and Adipogenic Differentiation of Porcine Intramuscular Adipocytes

The meat quality of animal products is closely related to the intramuscular fat content. Aquaglyceroporin (AQP) defines a class of water/glycerol channels that primarily facilitate the passive transport of glycerol and water across biological membranes. In this study, the AQP3 protein of the AQP family was mainly studied in the adipogenic function of intramuscular adipocytes in pigs. Here, we found that AQP3 was increased at both mRNA and protein levels upon adipogenic stimuli in porcine intramuscular adipocytes in vitro. Western blot results showed knockdown of AQP3 by siRNA significantly suppressed the expression of adipogenic genes (PPARγ, aP2, etc.), repressed Akt phosphorylation, as well as reducing lipid accumulation. Furthermore, deletion of AQP3 by siRNA significantly downregulated expression of cell cycle genes (cyclin D, E), and decreased the number of EdU-positive cells as well as cell viability. Collectively, our data indicate that AQP3 is of great importance in both adipogenic differentiation and proliferation in intramuscular adipocytes, providing a potential target for modulating fat infiltration in skeletal muscles.

Feeding sows resistant starch during gestation and lactation impacts their faecal microbiota and milk composition but shows limited effects on their progeny

Background

Establishment of a beneficial microbiota profile for piglets as early in life as possible is important as it will impact their future health. In the current study, we hypothesized that resistant starch (RS) provided in the maternal diet during gestation and lactation will be fermented in their hindgut, which would favourably modify their milk and/or gut microbiota composition and that it would in turn affect piglets’ microbiota profile and their absorptive and immune abilities.

Methods

In this experiment, 33% of pea starch was used in the diet of gestating and lactating sows and compared to control sows. Their faecal microbiota and milk composition were determined and the colonic microbiota, short-chain fatty acids (SCFA) production and gut health related parameters of the piglets were measured two days before weaning. In addition, their overall performances and post-weaning faecal score were also assessed.

Results

The RS diet modulated the faecal microbiota of the sows during gestation, increasing the Firmicutes:Bacteroidetes ratio and the relative abundance of beneficial genera like Bifidobacterium but these differences disappeared during lactation and maternal diets did not impact the colonic microbiota of their progeny. Milk protein concentration decreased with RS diet and lactose concentration increased within the first weeks of lactation while decreased the week before weaning with the RS diet. No effect of the dietary treatment, on piglets’ bodyweight or diarrhoea frequency post-weaning was observed. Moreover, the intestinal morphology measured as villus height and crypt depths, and the inflammatory cytokines in the intestine of the piglets were not differentially expressed between maternal treatments. Only zonula occludens 1 (ZO-1) was more expressed in the ileum of piglets born from RS sows, suggesting a better closure of the mucosa tight junctions.

Conclusion

Changes in the microbiota transferred from mother to piglets due to the inclusion of RS in the maternal diet are rather limited even though milk composition was affected.

Allogeneic CD4+CD25high T cells regulate obliterative bronchiolitis of heterotopic bronchus allografts in both porcinized and humanized mouse models

BACKGROUND

Bronchiolitis obliterans syndrome is caused by a fibroproliferative process in lung allografts resulting in irreversible damage. In this study, we induced obliterative bronchiolitis and studied the contribution of regulatory T cells to its development in immune-deficient mice receiving heterotopic porcine bronchus transplants, and major histocompatibility complex-mismatched porcine peripheral blood mononuclear cell. Furthermore, we aimed to corroborate our findings in a humanized mouse model.

METHODS

Heterotopic bronchus transplantation was performed in 33 NOD.rag(−/−)γc(−/−) mice, using miniature pigs as tissue donors.The recipient mice then either received saline (negative control), unsorted MHC-mismatched PBMC (positive control), PBMC enriched with CD4(+)CD25(high) cells or PBMC depleted of CD4(+)CD25(high) cells for reconstitution. The results were validated in 28 NOD.rag(−/−)γc(−/−) mice undergoing heterotopic human bronchus transplantation and reconstitution with allogeneic human PBMC.

RESULTS

Histological lesions similar to those typical for obliterative bronchiolitis developed in vivo after reconstitution with allogeneic PBMC and were more severe in animals engrafted with PBMC depleted of CD4(+)CD25(high) cells. In contrast, the group reconstituted with PBMC enriched with CD4(+)CD25(high) cells showed well-preserved histology. The results of the humanized model confirmed those obtained in the porcinized model.

CONCLUSIONS

In conclusion, both porcinized and humanized mouse models of heterotopic subcutaneous bronchus transplantation imitate the in vivo development of bronchiolitis obliterans syndrome-like lesions and reveal its sensitivity to T-cell regulation.

Probiotic Treatment Decreases the Number of CD14-Expressing Cells in Porcine Milk Which Correlates with Several Intestinal Immune Parameters in the Piglets

Modulating the mucosal immune system of neonates by probiotic treatment of their mothers is a promising approach which can only be investigated through the use of animal models. Here, we used sows and their piglets to investigate the impact of a bacterial treatment on the sow's milk and on the neonate piglet intestinal immune system. In previous experiments, feed supplementation of sows with the probiotic Enterococcus faecium NCIMB 10415 during pregnancy and lactation had been shown to affect intestinal microbiota and cytokine expression of the offspring during the suckling and weaning periods. We therefore investigated the composition of the milk from treated sows in comparison to samples from a control group. In treated sows, the amount of lactose increased, and the somatic cell numbers were reduced. In all milk samples, the percentage of cells expressing membranous CD14 (mCD14) was greater than the fractions of immune cells, indicating expression of mCD14 on mammary epithelial cells. However, in the milk of E. faecium-treated sows, mCD14(+) cells were reduced. Furthermore, the number of CD14(+) milk cells was positively correlated with the percentages of B cells and activated T cells in the ileal MLN of the piglets. This study provides evidence for the expression of mCD14 by the porcine mammary epithelium, and suggests an immunological effect of mCD14(+) milk cells on the piglets' intestinal immune system. Our study further suggests that mCD14(+) mammary epithelial cell populations can be modulated by probiotic feed supplementation of the sow.

The effect of leptin on luteal angiogenic factors during the luteal phase of the estrous cycle in goats

Fibroblast growth factor 2 (FGF2), angiopoietin 1 (Ang1), and vascular endothelial growth factor (VEGF) are angiogenic factors implicated in the vascular development of the corpus luteum (CL). Each factor is regulated or influenced by leptin in non-ovarian tissues. Moreover, leptin and its receptor, ObRb, have been identified in luteal tissue throughout the luteal phase. Therefore, leptin is hypothesized to influence luteal vasculature through the regulation of FGF2, Ang1, and VEGF. Multiparous, cycling crossbred female goats (does) were allocated to early (n=12), mid (n=8), and late (n=11) stages of the luteal phase for CL collection. Luteal tissue was harvested and either snap frozen in liquid N2, paraffin embedded, or cultured with leptin (0, 10(-12), 10(-11), 10(-10), 10(-9), 10(-8)M). Tissue was analyzed for FGF2, Ang1, VEGF, ObRb, and leptin expression. Angiopoietin 1, FGF2, VEGF expression was higher (P≤0.001) in the mid-luteal stage than the early stage. Expression decreased (P≤0.001) during the late luteal stage with the exception of VEGF, which remained elevated. In contrast, leptin and ObRb were lowest (P≤0.003) during the mid-luteal stage compared to the early and late stages. All factors were detected in and/or around vessels in early stage tissue compared to mid and late stages. Leptin stimulated (P≤0.02) Ang1, FGF2, and VEGF expression only in early stage luteal cultures. Collectively, these data provide evidence that leptin may be involved in the luteal angiogenic process during the early stage of CL formation.

Autocrine and paracrine mechanisms of prostaglandin E₂ action on trophoblast/conceptus cells through the prostaglandin E₂ receptor (PTGER2) during implantation

The conceptus and endometrium secrete large amounts of prostaglandin E₂ (PGE₂) into the porcine uterine lumen during the periimplantation period. We hypothesized that PGE₂ acts on conceptus/trophoblast cells through auto- and paracrine mechanisms. Real-time RT-PCR analysis revealed that PGE₂ receptor (PTGER)2 mRNA was 14-fold greater in conceptuses/trophoblasts on days 14-25 (implantation and early placentation period) vs preimplantation day 10-13 conceptuses (P < .05). Similarly, expression of PTGER2 protein increased during implantation. Conceptus expression of PTGER4 mRNA and protein did not differ on days 10-19. PGE₂ stimulated PTGER2 mRNA expression in day 15 trophoblast cells through PTGER2 receptor signaling. PGE₂ elevated aromatase expression and estradiol-17β secretion by trophoblast cells. Moreover, PGE₂ and the PTGER2 agonist, butaprost, increased the adhesive capacity of both human HTR-8/SVneo trophoblast and primary porcine trophoblast cells to extracellular matrix. This PGE₂-induced alteration in trophoblast cell adhesion to extracellular matrix was abolished by incubation of these cells with AH6809 (PTGER2 antagonist), ITGAVB3-directed tetrapeptide arg-gly-asp-ser or integrin ITGAVB3 antibody. PGE₂ stimulated adhesion of porcine trophoblast cells via the estrogen receptor and MEK/MAPK signaling pathway. PGE₂ induced phosphorylation of MAPK1/MAPK3 through PTGER2 and up-regulated expression of cell adhesion proteins such as focal adhesion kinase and intercellular adhesion molecule-1. Our study indicates that elevated PGE₂ in the periimplantation uterine lumen stimulates conceptus PTGER2 expression, which in turn promotes trophoblast adhesion via integrins, and synthesis and secretion of the porcine embryonic signal estradiol-17β. Moreover, the mechanism through which PGE₂ increases trophoblast adhesion is not species specific because it is PTGER2- and integrin-dependent in both porcine and human trophoblast cells.

Effect of conceptus on expression of prostaglandin F2α receptor in the porcine endometrium

Increased synthesis of prostaglandin F(2α) (PGF(2α)) in the endometrium and conceptus during the implantation period results in elevated concentration of PGF(2α) in the uterine lumen in pregnant gilts. PGF(2α) exerts its effects through PGF(2α) receptor (PTGFR), a G-protein-coupled receptor. However, besides studies concerning the function of PTGFR in endometrial abnormalities, the role of PTGFR in the endometrium during early pregnancy has not been elucidated. Therefore, the aim of this study was: (1) to evaluate the profile of PTGFR gene and protein expression in the porcine endometrium during early pregnancy and the estrous cycle; (2) to determine if the effect of conceptus on PTGFR expression is dependent on type of endometrial cells-luminal epithelial (LE) or stromal (ST) cells; and (3) to elucidate if the putative effect of conceptus on endometrial PTGFR expression is mediated by estrogen receptor. We evaluated the expression pattern of PTGFR gene and protein in the endometrium during day 9, 11, 12, 15, and 18 of the estrous cycle and pregnancy (N = 4-6 per group). The expression of PTGFR mRNA was greater on day 18 of pregnancy and the estrous cycle (vs. days 9-15 of the estrous cycle and pregnancy, P < 0.05). Expression of PTGFR protein was approximately 10-fold upregulated in the endometrium on day 15 of pregnancy when compared with day 15 of the estrous cycle (P < 0.01). Endometrial expression of PTGFR protein increased from day 12 to 18 of pregnancy (P < 0.05). PTGFR mRNA was expressed in LE and ST cells. In a subsequent experiment, we used a coculture model in which LE cells were cultured on collagen-coated inserts placed in wells plated with ST cells. Day 11 or 15 conceptus-exposed medium (CEM) elevated expression of PTGFR mRNA (2- and 1.5-fold, respectively, P < 0.05) in LE cells cocultured with ST cells. CEM did not have an effect on PTGFR mRNA expression in ST cells. The 11-day CEM-induced increase of PTGFR mRNA was abolished by incubation of LE cells in the presence of the estrogen receptor antagonist (ICI-182,780; P < 0.01). Summarizing, the conceptus upregulated expression of PTGFR in the endometrium during the implantation period. Moreover, this study indicates that expression of PTGFR gene was elevated in LE cells of endometrium by embryonic signal of estradiol. Our results suggest para- and autocrine effects of PGF(2α) through its receptor PTGFR in the porcine endometrium, especially in luminal epithelium which is in direct contact with the conceptus during the implantation period.

Interleukin-18 expression in pig salivary glands and salivary content changes during acute immobilization stress

Interleukin-18 (IL-18) has recently been considered a promising marker of stress responses. In this study, to evaluate IL-18 as a noninvasive stress marker in pigs, we investigated the expression of IL-18 in porcine salivary glands and its presence in saliva, and its dynamics during acute immobilization stress in pigs. IL-18 mRNA was detected robustly in the pig salivary glands by RT-PCR. Immunohistochemical staining of IL-18 protein expression revealed that the expression patterns differed among the three types of salivary glands (parotid, submandibular, and sublingual gland). IL-18 was also detected in pig saliva by ELISA, and a diurnal rhythm with a peak in the afternoon was observed. The IL-18 concentration in saliva was significantly increased during a 60-min acute immobilization stress in thirteen 5-month-old pigs. These results are the first evidence of a stress-related change of IL-18 in pig saliva. Salivary IL-18 may thus become a useful noninvasive marker for the evaluation of acute stress in pigs.

Effect of heat challenge on peripheral blood mononuclear cell viability: comparison of a tropical and temperate pig breed

We evaluated the effect of heat challenge on cell viability, concanavalin A-induced proliferation and heat shock protein (HSPs) mRNA expression in peripheral mononuclear blood cells (PBMC) isolated from Creole (CR) and Large White (LW) pigs. The PBMCs were cultured for 9 h at 37 °C before being subjected to heat challenge: (1) at 42 °C or 45 °C for 2, 4, 6 and 9 h to monitor cell viability;(2) at 45 °C for 2 and 9 h followed by stimulation for 24 h at 37 °C with concanavalin A to evaluate mitogen-induced proliferation; and (3) at 45 °C for 3, 6 and 9 h to measure induction of HSP70.2 and HSP90 mRNA. Cell viability was affected by breed and temperature (P < 0.01), and the viability decrease caused by heat challenge was greater for LW than CR pigs. For mitogen-stimulated PBMCs, incubation at 45 °C reduced lymphoblastogenesis equally in both breeds (P < 0.01). Although heat challenge for 3 and 6 h at 45°C induced expression of HSP70.2 and HSP90 mRNA, no breed difference was observed. In conclusion, differences in heat resistance between these two breeds at the whole organism level are reflected at the cellular level. Neither HSP70.2 nor HSP90 mRNA expression levels explain this effect.

Quantitative analysis of inflammatory cytokines expression in peripheral blood mononuclear cells of the ferret (Mustela putorius furo) using real-time PCR

This study describes the expression pattern of cytokines, interferon-gamma (IFN-gamma), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and IL-10, produced by LPS stimulation in peripheral blood mononuclear cells (PBMCs) of the ferret (Mustela putorius furo). Real-time PCR was used with TaqMan probes, which were modified by dual-labeled probes (TAMRA/FAM), quantitative analysis of cytokine mRNA comparing the cytokine with the housekeeping gene, ferret GAPDH, as the relative C(t) value. Expression peaks of IFN-gamma, TNF-alpha, IL-6 mRNA occurred 2 h after LPS stimulation, whereas the IL-10 peak was 8 h post-LPS. In the present study, peak cytokine expression was detected within 8 h, similar to several other mammalian studies. This current study provides baseline information on inflammatory cytokines of ferret PBMCs.

Cytolethal distending toxin type I and type IV genes are framed with lambdoid prophage genes in extraintestinal pathogenic Escherichia coli

Five types of cytolethal distending toxin (CDT-I to CDT-V) have been identified in Escherichia coli. In the present study we cloned and sequenced the cdt-IV operon and flanking region from a porcine extraintestinal pathogenic E. coli (ExPEC) strain belonging to serogroup O75. We confirmed that similar to other CDTs, CDT-IV induced phosphorylation of host histone H2AX, a sensitive marker of DNA double-strand breaks, and blocked the HeLa cell cycle at the G(2)-M transition. The cdt-IV genes were framed by lambdoid prophage genes. We cloned and sequenced the cdt-I operon and flanking regions from a human ExPEC O18:K1:H7 strain and observed that cdt-I genes were also flanked by lambdoid prophage genes. PCR studies indicated that a gene coding for a putative protease was always associated with the cdtC-IV gene but was not associated with cdtC genes in strains producing CDT-I, CDT-III, and CDT-V. Our results suggest that the cdt-I and cdt-IV genes might have been acquired from a common ancestor by phage transduction and evolved in their bacterial hosts. The lysogenic bacteriophages have the potential to carry nonessential "cargo" genes or "morons" and therefore play a crucial role in the generation of genetic diversity within ExPEC.

The novel porcine Lactobacillus sobrius strain protects intestinal cells from enterotoxigenic Escherichia coli K88 infection and prevents membrane barrier damage

Lactobacilli have a potential to overcome intestinal disorders; however, the exact mode of action is still largely unknown. In this study, we have used the intestinal porcine intestinal IPEC-1 epithelial cells as a model to investigate a possible protective activity of a new Lactobacillus species, the L. sobrius DSM 16698(T), against intestinal injury induced by enterotoxigenic Escherichia coli (ETEC) K88 infection and the underlying mechanisms. Treatment of infected cells with L. sobrius strongly reduced the pathogen adhesion. L. sobrius was also able to prevent the ETEC-induced membrane damage by inhibiting delocalization of zonula occludens (ZO)-1, reduction of occludin amount, rearrangement of F-actin, and dephosphorylation of occludin caused by ETEC. RT-PCR and ELISA experiments showed that L. sobrius counteracted the ETEC-induced increase of IL-8 and upregulated the IL-10 expression. The involvement of IL-8 in the deleterious effects of ETEC was proven by neutralization of IL-8 with a specific antibody. A crucial role of IL-10 was indicated by blockage of IL-10 production with neutralizing anti-IL-10 antibody that fully abrogated the L. sobrius protection. L. sobrius was also able to inhibit the internalization of ETEC, which was likely favored by the leaking barrier. The protective effects were not found with L. amylovorus DSM 20531(T) treatment, a strain derived from cattle waste but phylogenetically closely related to L. sobrius. Together, the data indicate that L. sobrius exerts protection against the harmful effects of ETEC by different mechanisms, including pathogen adhesion inhibition and maintenance of membrane barrier integrity through IL-10 regulation.

Alpha interferon is a powerful adjuvant for a recombinant protein vaccine against foot-and-mouth disease virus in swine, and an effective stimulus of in vivo immune response

The adjuvant effect of porcine interferon-alpha (PoIFN-alpha) was examined in swine vaccinated with a recombinant FMD protein vaccine named IgG-FMDV, which contains the swine IgG single heavy chain constant region and an immunogenic peptide of serotype O FMDV. The PoIFN-alpha gene was cloned into pcDNA3 vector and the recombinant plasmid was incorporated into cationic liposomes by a dehydration and rehydration procedure to use as an adjuvant, injected together with low-dose IgG-FMDV. This procedure resulted in strong induction of FMDV-specific neutralizing antibody and significant T-cell-mediated immune responses, whereas only a modest humoral and cellular response was observed with low-dose vaccine alone. As an adjuvant for the protein vaccine, PoIFN-alpha induced strong inflammatory cytokines production in vivo and the results denoted that IFN-adjuvant and our vaccines could drive the immune response toward Th1 type responses. The data of ELISA suggests that the recombinant protein vaccine synergizes with the IFN-adjuvant to produce endogenous IFN in vivo. In response to viral challenge, all control animals developed viremia and lesions, whereas all animals received IFN-adjuvant+IgG-FMDV were protected and nonstructural protein antibody in this group could not be detected by 14 days post-challenge (dpc). Our studies indicate that porcine IFN-alpha is a powerful adjuvant for recombinant FMD protein vaccine and could aid in vaccination against FMDV in swine.

Effects of added fermentable carbohydrates in the diet on intestinal proinflammatory cytokine-specific mRNA content in weaning piglets

There is increasing evidence showing that dietary supplementation with prebiotics can be effective in the treatment of intestinal inflammation. Because weaning time is characterized by rapid intestinal inflammation, this study investigated the effect of a diet supplemented with a combination of 4 fermentable carbohydrates (lactulose, inulin, sugarbeet pulp, and wheat starch) on the mRNA content of proinflammatory cytokines in newly weaned piglets. Cytokines (IL-1beta, IL-6, IL-8, IL-12p40, IL-18, and tumor necrosis factor-alpha) were analyzed using a semiquantitative reverse-transcription PCR technique on d 1, 4, and 10 in the ileum and colon of piglets fed either a test diet (CHO) or a control diet. In addition to the diet, the effect of enforced fasting on cytokine mRNA content was also evaluated. No effect of fasting was observed on the pro-inflammatory cytokine mRNA content. Our results showed that the CHO diet induced an up-regulation of IL-6 mRNA content in the colon of piglets 4 d postweaning. This up-regulation was specific for the animals fed the CHO diet and was not observed in animals fed the control diet. An increase in IL-1beta mRNA content was also observed on d 4 postweaning in all of the piglets. Correlations between proinflammatory cytokines and the end-products of fermentation indicated that the regulation of cytokines may be linked with some of the fermentation end-products such as branched-chain fatty acids, which are in turn end-products of protein fermentation.

Mycotoxin fumonisin B1 selectively down-regulates the basal IL-8 expression in pig intestine: in vivo and in vitro studies

Fumonisin B(1) (FB(1)) is a mycotoxin produced by Fusarium verticillioides and F. proliferatum, common contaminants of maize. FB(1) causes toxicological effects in laboratory and domestic animals including pigs. The gastrointestinal tract represents a barrier encountered by exogenous food compounds. The purpose of our study was to determine FB(1) effects on intestinal immune response. Nine recently weaned piglets orally received 0.5 mg of purified toxin/kg of body weight/day for 7 days, while eight other animals were kept as controls. After necropsy, ileal samples were analyzed for five pro-inflammatory cytokines mRNA expression by RT-PCR. No difference was observed for IL-1beta, IL-6, IL-12 and TNF-beta mRNA levels between control and FB(1)-treated animals. In contrast, FB(1) treatment induced a significant down-regulation of the expression of IL-8 mRNA in the pig ilea. The effect of FB(1) on the IL-8 expression was also examined in the porcine intestinal epithelial cell line IPEC-1. FB(1) decreases the expression of IL-8, both at the mRNA and protein levels, in a dose-dependant manner. Taken together, our data demonstrate that FB(1) alters the intestinal immune response by decreasing the level of IL-8. This may contribute to the increased intestinal colonization by pathogenic Escherichia coli that was observed in FB(1)-treated pigs and may have implications for humans/animals consuming FB(1)-contaminated food/feed.

Swine infection with Trichinella spiralis: Comparative analysis of the mucosal intestinal and systemic immune responses

The immune protective response developed by swine against Trichinella spiralis is not yet fully understood, particularly at the mucosal level. This study aimed to characterise intestinal immunity to T. spiralis by comparison with the systemic response in specifically pathogen-free pigs. For this purpose, the kinetics of cytokine and antibody production were assessed in the intestinal mucosa and serum of swine infected with T. spiralis for up to 60 days post-infection (dpi). An ex vivo model of jejunum mucosa culture was used to collect the supernatant as a source of antibodies (Abs). Mucosal antibodies were observed by Western blot from 15 dpi, while serum antibodies were expressed from 20 dpi. Both sources of antibodies initially recognized a 110 kDa protein, followed by the identification of 35, 43/46 and 55/59 kDa proteins. IgG1 and IgA antibodies were strongly expressed within the mucosa. The expression levels of Type 1 (IFN-gamma, IL-12), Type 2 (IL-4, IL-6), pro-inflammatory (TNF-alpha) and regulatory (IL-10, TGF-beta) cytokines were assessed by RT-PCR in the intestinal mucosa and spleen. Both IL-10 and IFN-gamma mRNA levels were increased in mucosa, whereas IL-6 and IL-12 mRNA were expressed in spleen. Taken together, these results demonstrated a mixed Type 1/Type 2 profile, the Type 2 profile being dominant in the mucosa.

Sex-related differences in the immune response of weanling piglets exposed to low doses of fumonisin extract

Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium verticillioides, a fungus that commonly contaminates maize. Sex-related effects of FB1 have been observed with respect to carcinogenicity in rodents, to performances in pigs and immunosuppression in mice. In the present study the sex-related effect of FB1 on the pig immune response was determined. Female and castrated male piglets received for 28 d either control feed or feed contaminated with 8 mg FB1/kg feed in the form of F. verticillioides culture material. At day 7 and day 21, animals were immunised subcutaneously with a Mycoplasma agalactiae vaccine. Ingestion of FB1-contaminated feed significantly decreased weight gain in males but had no effect in females. No sex-related difference was observed in biochemical parameters, but a higher level of creatinine was noted in toxin-treated animals. FB1 also altered the pig immune response in a sex-specific manner. In males, ingestion of FB1-contaminated feed significantly decreased specific antibody levels after vaccination as well as the mRNA expression level of IL-10. In females, the toxin has no effect on specific antibodies or on cytokine mRNA levels. The results of the present study indicate that FB1 is immunosuppressive in pigs. The magnitude of this FB1-induced immunosuppression is highly dependent on sex, with males being more susceptible than females.

Glucose transporter 8 (GLUT8) from the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae)

We have cloned the fire ant glucose transporter 8 (GLUT8) cDNA providing the first molecular characterization of a GLUT8 in insects. Glucose is a poly-alcohol and, due to its high hydrophilicity, cannot move across cell membranes. GLUT8 is a putative facilitative transporter for the cellular import and export of glucose. The complete 2,974-bp cDNA encodes a 501-residue protein with a predicted molecular mass of 54.8 kDa. Transcripts were detected in the brain, midgut, hindgut, Malpighian tubule, fat body, ovary, and testis. The highest transcriptional expression was found in fat body. Northern blot analysis revealed different transcript sizes in mated queen brains, alate female ovaries, and male testes. We propose that four other sequences obtained from insect genome projects from the honey bee Apis mellifera (ENSAPMP00000006624), the malaria mosquito Anopheles gambiae (EAA11842), and the fruit fly Drosophila melanogaster (AAQ23604 and AAM52591) are likely the orthologues of the fire ant GLUT8. Phylogenetic relationships in insect glucose transporters are presented.

Proinflammatory cytokine and chemokine modulation byStreptococcus suisin a whole-blood culture system

Streptococcus suis is an important swine and human pathogen. Inflammation, a hallmark of S. suis infection, is thought to be responsible for most clinical signs of meningitis, septicaemia and sudden death. In this work, using a porcine whole blood model, S. suis serotype 2 was shown to trigger the release of several pro-inflammatory cytokines as evaluated by reverse transcriptase-PCR and enzyme-linked immunosorbent assay. Although individual variations were observed among different S. suis strains, no correlations were observed between the strain origin/phenotype and cytokine levels. Live bacteria induced higher tumour necrosis factor alpha, interleukin-1 beta (IL-1beta) and IL-6 levels than did heat-killed bacteria. In contrast, heat-killed bacteria stimulated higher levels of IL-8 and monocyte chemotactic protein one (MCP-1). The bacterial cell wall was observed to be the major cytokine-inducting components, whereas capsule expression was important for MCP-1 activation. The presence of specific antibodies suppressed bacterial growth resulting in significantly reduced levels of cytokine production. Thus, antibody-mediated bacterial phagocytosis combined with suppressed inflammation may be beneficial for infection control strategies. We provide first evidence of S.suis-induction of pro-inflammatory swine cytokines and demonstrate the strength and relevance of the whole blood culture systems in the investigation of S. suis modulation of cytokine production.

The short neuropeptide F-like receptor from the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae)

In invertebrates, neuropeptide F (NPF) peptides share structural similarity with vertebrate neuropeptide Y, which regulates food consumption, circadian rhythms, anxiety, and other physiological processes. The insect neuropeptide F receptors belong to the G protein-coupled receptor (GPCR) rhodopsin family. We have cloned the fire ant putative short NPF receptor using PCR and RACE methods. The complete 2,185-bp cDNA encodes a 387-residue protein with a predicted GPCR seven transmembrane region structure. We propose that the sequence of the honey bee short NPF receptor, which has not yet been annotated, encodes a protein of 393 residues. In fire ant mated queens, receptor transcripts were detected in the brain, midgut, hindgut, Malpighian tubules, fat body, and ovaries. The highest transcriptional expression was found in the brain. The downregulation of the fire ant short NPF receptor transcriptional expression in the brain with starvation suggests that the short NPF signal transduction cascade may play a role in feeding regulation in fire ant mated queens.

Quantitation of ovine cytokine mRNA by real-time RT–PCR

In this study we describe for the first time the dynamics of the expression of the cytokines, IL-1beta, IL-12p40, TNFalpha in ovine dendritic cells and macrophages after LPS stimulation. Real time RT-PCR was used for the quantitation of these cytokines and IL-4 and IFNgamma as well as two potential housekeeping genes (HKG), ATPase and GAPDH, in mRNAs from ovine leucocyte populations. Both dual-labelled probes (TAMRA/FAM) and SYBR Green assays were utilised, using a Corbett Research RotorGene and ABI 7700 machine. In order to quantitate each cytokine in our assays all C(T) values were compared to a standard curve generated using plasmid DNA containing the cytokine of interest. To validate our assays, concanavalin A-stimulated peripheral blood mononuclear cells (PBMCs) and LPS-stimulated monocyte-derived dendritic cells (MoDC) and monocyte-derived macrophages (MDMØ) were examined. We found that peak cytokine mRNA expression was between 3 and 6 h for the cytokines examined except for IL-12p40 where peak cytokine release was around 12 h post-stimulation in MDMØ and PBMCs. However, in MoDCs, peak IL-12p40 mRNA expression was observed within 3-6 h. We have identified a sensitive and reliable method for the identification of ovine cytokine mRNAs.

Establishment, differentiation, electroporation, viral transduction, and nuclear transfer of bovine and porcine mesenchymal stem cells

Mesenchymal stem cells (MSCs) reside in the bone marrow and have the potential for multilineage differentiation, into bone, cartilage, and fat, for example. In this study, bovine and porcine MSCs were isolated, cultured to determine their replication ability, and differentiated with osteogenic medium and 5-azacytine. Both bovine and porcine undifferentiated MSCs were electroporated and virally transduced to test the efficiency of genetic modification and the maintainance of differentiation ability thereafter. Nuclear transfer experiments were carried out with bovine and porcine MSCs, both at the undifferentiated state and following differentiation. Our results indicate that bovine and porcine MSCs have limited lifespans in vitro--approximately 50 population doublings. They can be efficiently differentiated and characterized along the osteogenic lineage by morphology, alkaline phosphatase, Von Kossa, oil red stainings, and RT-PCR. Electroporation and selection induce high levels of EGFP expression in porcine but not in bovine MSCs. Following genetic modification, MSCs retain their pluridifferentiation ability as parental cells. Cloned embryos derived from bovine and porcine undifferentiated MSCs and their derivatives along the osteogenic lineage give rise to consistently high preimplantation development comparable to adult fibroblasts.

Characterization of a porcine intestinal epithelial cell line for in vitro studies of microbial pathogenesis in swine

In vitro studies on the pathogenesis in swine have been hampered by the lack of relevant porcine cell lines. Since many bacterial infections are swine-specific, studies on pathogenic mechanisms require appropriate cell lines of porcine origin. We have characterized the permanent porcine intestinal epithelial cell line, IPEC-J2, using a variety of methods in order to assess the usefulness of this cell line as an in vitro infection model. Electron microscopic analyses and histochemical staining revealed the cells to be enterocyte-like with microvilli, tight junctions and glycocalyx-bound mucin. The functional integrity of monolayers was determined by transepithelial electrical resistance (TEER) measurements. Both commensal bacteria and important bacterial pathogens were chosen for study based on their principally different infection mechanisms: obligate extracellular Escherichia coli, facultative intracellular Salmonella and obligate intracellular Chlamydia. We determined the colonization and proliferation of the bacteria on and within the host cells and monitored the host cell response. We verified the expression of mRNAs encoding the cytokines IL-1alpha, -6, -7, -8, -18, TNF-alpha and GM-CSF, but not TGF-beta or MCP-1. IL-8 protein expression was enhanced by Salmonella invasion. We conclude that the IPEC-J2 cell line provides a relevant in vitro model system for porcine intestinal pathogen-host cell interactions.

Quantitative simultaneous multiplex real-time PCR for the detection of porcine cytokines

We have established an easy real-time PCR assay, which allows the precise quantification of changes in the expression level of 6 relevant porcine cytokines, and 3 housekeeping genes. This assay simultaneously detects 9 sequences by measuring 3 x 3 targets in a triplex-format. The mRNA of the lymphokines IL-2, IL-4, IL-10, and IFN-gamma, of the proinflammatory cytokines IL-1alpha and IL-6, and of the housekeeping genes are quantified using TaqMan-probes by means of standard dilution series on the iCycler iQ. The standard consists of equal aliquots of the experimental cDNAs under investigation. Simultaneously the most suitable combination of 3 out of the four housekeeping genes beta-actin, HPRT, GAPDH, and cyclophilin can be selected, and their averaged expression values constitute a normalisation factor. The raw data of all targets of interest is then calculated relative to this normalisation factor, making eventual changes of the relative expression level of the single housekeeping genes controllable and quantifiable. We have applied this assay to quantify changes in the cytokine mRNA levels of porcine stimulated with various concentrations of LPS and ConA, known to induce different cytokine expression patterns. We have shown, that even small differences in the expression level (less than 2-fold) can be precisely quantified, and reveal statistically significant changes, when using the normalisation factor. This assay will be useful for studying changes in the expression of relevant porcine cytokines and will help to further improve the investigation of immune responses in the pig.

Age, gender and litter-related variation in T-lymphocyte cytokine production in young pigs

The capacity of farm animals to produce cytokines could be an important determinant of robustness and health. From research in rodents and humans it appears that the production and the balance of T helper 1 (Th1) and T helper 2 (Th2)-type cytokines influences susceptibility to autoimmune and infectious diseases. It is known that pigs show a large variation in many immune response parameters. So far the extent of individual variation in the production of Th1- and Th2-type cytokines in commercial outbred pigs has not been reported. In the current experiment we determined mRNA expression, as well as protein production of cytokines in 32 pigs from eight litters. From each litter two male and two female pigs were tested at 2, 5 and 8 weeks of age. Two Th1-type cytokines, interleukin (IL)-2 and interferon (IFN)-gamma, and two Th2-type cytokines, IL-4 and IL-10, were measured after phytohaemagglutinin (PHA)-stimulation of blood mononuclear cells. Cytokine production and the Th1/Th2-ratio were highly variable. The variation in cytokine protein production was moderately consistent across ages, i.e. pigs that produced high levels of cytokine at 2 weeks of age tended to do so as well at 5 and 8 weeks of age. Cytokine production tended to increase with age, and gilts and boars differed in their IL-2/IL-4 ratio. Unexpectedly, age, gender and litter effects often differed for mRNA and protein production data. We hypothesize that cytokine production is a consistent trait in pigs, especially at the protein production level. Future investigations in more animals and across a wider age range are necessary.

Host immune status influences the development of attaching and effacing lesions in weaned pigs

Attaching and effacing Escherichia coli (AEEC) has been associated with naturally occurring attaching and effacing (A/E) lesions in weaned pigs, and although A/E lesions have been experimentally reproduced in newborn piglets, such lesions have been much more difficult to induce in older conventional pigs. Hence, the aim of this study was to examine the effect of oral administration of dexamethasone on the development of A/E lesions in weaned pigs challenged with a porcine enteropathogenic E. coli (PEPEC) strain and to investigate the involvement of local intestinal cytokine response. Dexamethasone, given orally at a dosage of 3 mg kg of body weight(-1), significantly enhanced both the colonization of the challenge strain and the prevalence of foci of intimately adherent bacteria, resulting in extensive A/E lesions in the ileum, cecum, and colon of challenged pigs. We also confirmed the expression of both intimin and Tir by PEPEC strain ECL1001 in A/E lesions in vivo, which is, to our knowledge, the first report of the involvement of the latter proteins in any AEEC infections in vivo. Moreover, semiquantitative reverse transcription-PCR demonstrated that interleukin 1beta (IL-1beta), IL-6, IL-8, and, to a lesser extent, IL-12p40 are significantly upregulated in the ileum following challenge with strain ECL1001, whereas dexamethasone blocks such upregulation. Taken together, our results strongly suggested that host immune status influences the development of A/E lesions in weaned pigs, and it appears that IL-1beta, IL-6, IL-8, and, to a lesser extent, IL-12p40 are expressed during infection of weaned pigs by PEPEC and may contribute to the natural resistance of the host against PEPEC infection.

Oral exposure to culture material extract containing fumonisins predisposes swine to the development of pneumonitis caused by Pasteurella multocida

Fumonisin B(1) (FB(1)) is a mycotoxin produced by Fusarium verticillioides and F. proliferatum that commonly occurs in maize. In swine, consumption of contaminated feed induces liver damage and pulmonary edema. Pasteurella multocida is a secondary pathogen, which can generate a respiratory disorder in predisposed pigs. In this study, we examined the effect of oral exposure to fumonisin-containing culture material on lung inflammation caused by P. multocida. Piglets received by gavage a crude extract of fumonisin, 0.5mg FB(1)/kg body weight/day, for 7 days. One day later, the animals were instilled intratracheally with a non toxin producing type A strain of P. multocida and followed up for 13 additional days. Pig weight and cough frequency were measured throughout the experiment. Lung lesions, bronchoalveolar lavage fluid (BALF) cell composition and the expression of inflammatory cytokines were evaluated at the autopsy. Ingestion of fumonisin culture material or infection with P. multocida did not affect weight gain, induced no clinical sign or lung lesion, and only had minimal effect on BALF cell composition. Ingestion of mycotoxin extract increased the expression of IL-8, IL-18 and IFN-gamma mRNA compared with P. multocida infection that increased the expression of TNF-alpha. The combined treatment with fumonisin culture material and P. multocida delayed growth, induced cough, and increased BALF total cells, macrophages and lymphocytes. Lung lesions were significantly enhanced in these animals and consisted of subacute interstitial pneumonia. TNF-alpha, IFN-gamma and IL-18 mRNA expression was also increased. Taken together, our data showed that fumonisin culture material is a predisposing factor to lung inflammation. These results may have implications for humans and animals consuming FB(1) contaminated food or feed.

Egg white derivatives induce tumor necrosis factor-α expression in porcine peripheral blood mononuclear cells

Porcine PBMC derived phagocytic activity in peripheral blood polymorphonuclear cells (PMN) induced by egg white derivatives (EWD) treatment was analyzed at the protein and mRNA level. EWD alone failed to induce phagocytic activity of PMN measured by flow cytometry. But PMN phagocytosis was enhanced by culture supernatant from PBMC treated with EWD, human (h)rTNF-alpha and porcine (p)rIL-1beta, respectively. To identify this phagocytic inducing factor, the culture supernatant was partially purified by gel filtration. Only fraction 8 revealed the enhanced PMN phagocytic activity. This fraction also had a high cross-reactivity with anti-prTNF-alpha polyclonal (p)Ab but not with anti-prIL-1beta pAb, as measured by ELISA, indicating that the culture supernatant from PBMC treated with EWD was independent from IL-1beta. The enhanced PMN phagocytic activity of fraction 8 was also inhibited by anti-prTNF-alpha pAb. Both fraction 8 and hrTNF-alpha produced a single protein band between 16 and 18kDa upon analysis by sodium-dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting using anti-prTNF-alpha pAb, suggesting that the promoter of PMN phagocytosis is TNF-alpha, a 16-18 kDa protein produced by EWD-stimulated PBMC. Porcine TNF-alpha mRNA expression in porcine PBMC analyzed by RT-PCR was also increased by addition of EWD. This study strongly suggests that the immunoenhancing effect of EWD on the phagocytic response of porcine PMN is mediated through TNF-alpha produced by PBMC stimulated with EWD. In addition, the expression of porcine TNF-alpha on PBMC is also increased when stimulated with EWD.

Increased production of proinflammatory cytokines following infection with porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae

Induction of the proinflammatory cytokines interleukin-1 (IL-1) (alpha and beta), IL-6, IL-8, IL-10, IL-12, and tumor necrosis factor alpha (TNF-alpha) in pulmonary alveolar macrophages (PAMs) was assessed following experimental infection with porcine reproductive and respiratory syndrome virus (PRRSV) and/or Mycoplasma hyopneumoniae by using in vivo and in vitro models. The in vivo model consisted of pigs infected with PRRSV and/or M. hyopneumoniae and necropsied at 10, 28, or 42 days postinfection. Pigs infected with both pathogens had a greater percentage of macroscopic lung lesions, increased clinical disease, and slower viral clearance than pigs infected with either pathogen alone. The pigs infected with both PRRSV and M. hyopneumoniae had significantly increased levels of mRNA for many proinflammatory cytokines in PAMs collected by bronchoalveolar lavage (BAL) at all necropsy dates compared to those in uninfected control pigs. Increased levels of IL-1beta, IL-8, IL-10, and TNF-alpha proteins in BAL fluid, as measured by enzyme-linked immunosorbent assay, confirmed the increased cytokine induction induced by the pathogens. An in vitro model consisted of M. hyopneumoniae-inoculated tracheal ring explants cultured with PRRSV-infected PAMs. PAMs were harvested at 6 or 15 h postinfection with either or both pathogens. The in vitro study detected increased IL-10 and IL-12 mRNA levels in PAMs infected with PRRSV at all time periods. In addition, IL-10 protein levels were significantly elevated in the culture supernatants in the presence of M. hyopneumoniae-inoculated tracheal ring explants. The increased production of proinflammatory cytokines in vivo and in vitro associated with concurrent M. hyopneumoniae and PRRSV infection may play a role in the increased rates of pneumonia associated with PRRSV infection. The increased levels of IL-10 may be a possible mechanism that PRRSV and M. hyopneumoniae use to exacerbate the severity and duration of pneumonia induced by PRRSV and modulate the respiratory immune response.

Expression of mRNA encoding interleukin (IL)-10, IL-12p35 and IL-12p40 in lungs from pigs experimentally infected with Actinobacillus pleuropneumoniae

The expression of mRNA encoding interleukin (IL)-10, IL-12p35 and IL-12p40 was studied, by reverse transcription-polymerase chain reaction and by in situ hybridization with a non-radioactive digoxigenin-labelled cDNA probe, in formalin-fixed, paraffin-wax-embedded lung tissue from pigs experimentally infected with Actinobacillus pleuropneumoniae. Forty-eight 7-week-old colostrum-deprived pigs were randomly allocated to infected (n = 24) or control (n = 24) groups. Three pigs from each group were euthanized at 3, 6, 9, 12, 24, 36, 48 and 60 h post inoculation (hpi). IL-10 mRNA was detected in the lung at 3 hpi, numbers of cells positive for IL-10 increasing at 36 hpi. IL-12p35 mRNA was detected in the lung at 3 hpi, numbers of cells positive for IL-12p35 increasing at 36 and 48 hpi and rapidly decreasing thereafter whereas IL-12p40 mRNA was constitutively expressed at low levels during the experiment. Hybridization signals for IL-10, IL-12p35 and IL-12p40 were always associated with inflammation, in particular with macrophages and neutrophils within alveolar spaces. Expression of these cytokines was minimal in non-lesional lung of A. pleuropneumoniae-infected pigs and in normal lung from control pigs. In situ hybridization of A. pleuropneumoniae and these cytokines in serial sections of lung tissues indicated close co-localization of A. pleuropneumoniae and these cytokines in pleuropneumonia. The results suggest that the expression of IL-10 and IL-12 play a role in pathogenesis of A. pleuropneumoniae infection.

Immune response characteristics following emergency vaccination of pigs against foot-and-mouth disease

Pigs were vaccinated with the emergency inactivated foot-and-mouth disease virus (FMDV) vaccine--water-in-oil-in-water emulsion with Montanide ISA206--known to protect after 3-5 days. Peripheral blood leukocyte (PBL) sub-populations did not differ between vaccinates and controls post-vaccination. There was neither lymphopenia nor inflammatory reaction. FMDV-specific antibody and T lymphocyte activity developed in the vaccinates. Virus-induced Th1-like cytokine protein and mRNA (IFNgamma and IL-2) were identified, particularly IFNgamma. Th2-like cytokine protein and mRNA (IL-4 and IL-6) were also induced in an FMDV-specific manner. IL-10 was induced by both virus and mock antigen. The current emergency FMDV vaccine induces a diverse immune defence network--innate, and both Th1-like and Th2-like responses--without adverse reactions such as lymphopenia or inflammatory responses.

Immunostimulatory capacity of DNA vaccine vectors in porcine PBMC: a specific role for CpG-motifs?

With the development of DNA vaccines in pigs, the possibility was investigated that the nature and the amount of certain CpG-motifs present on plasmid DNA might have an effect on their immunostimulatory capacity. A panel of three CpG-oligodeoxynucleotides (ODN) and three eukaryotic expression vectors currently used in experimental DNA vaccines in pigs (pcDNA1, pcDNA3.1 and pCI) were screened for their immunostimulatory activity on porcine PBMC by evaluating in vitro the lymphocyte proliferative responses and cytokine profiles (IL-1alpha, IL-2, IL-4, IL-6, IL-10, IFN-gamma, TGF-beta, TNF-alpha). The vectors were chosen so that they differed in number and nature of certain CpG-motifs present on their backbone. CpG-ODN A (5'ATCGAT3') and to a lesser extend CpG-ODN C (5'AACGTT3') significantly enhanced the proliferation of porcine PBMC in contrast to CpG-ODN B (5'GACGTT3') where no effect was observed. Furthermore, CpG-ODN A significantly induced IL-6 and TNF-alpha together with elevated levels of IFN-gamma and IL-2 mRNA expression even though considerable heterogeneity was observed in the response of individual pigs. Comparison of the three vectors showed significantly increased proliferative responses for both pcDNA3.1 and pCI combined with a significant increase in IL-6 mRNA levels for pCI. For pcDNA1, proliferation was absent together with significantly decreased levels of IL-6 and IFN-gamma. CpG-ODN and plasmids both suppressed the TGF-beta and IL-1alpha mRNA expression. Taken together, these data confirm the identity of an optimal immunostimulating CpG-motif in pigs (5'-ggTGCATCGATGCAG-3') and demonstrates that the choice of the vector or the insertion of immunostimulatory motifs can be important in the future design of DNA vaccines in pigs, although further research is necessary to explore the possible link between certain CpG-motifs and the immunogenicity of DNA vaccines.

Nonviral monocyte chemoattractant protein-1 gene transfer improves arteriogenesis after femoral artery occlusion

Local infusion of recombinant monocyte chemoattractant protein-1 (MCP-1) has been shown to enhance collateral artery formation in rabbit and pig hindlimb models. Owing to clinical disadvantages of protein infusion, a nonviral, liposome-based MCP-1 gene transfer was developed. Collateralization in a porcine hindlimb model served to provide a proof-of-principle for the functional benefit of MCP-1 overexpression. Development of arterial conductance as a measure of functionally relevant collateralization was evaluated in occluded as well as untreated hindlimbs in each animal. At the time of occlusion, MCP-1 and control DNA/DC-30 lipoplexes were transferred to femoral arteries of Goettingen minipigs (two therapeutic MCP-1 groups: 2 and 4 microg and one control group), using the Infiltrator local drug-delivery device. At 2 weeks following occlusion, collateralization was determined as changes in peripheral haemodynamic conductance, peripheral over aortic blood pressure ratio and angiographically visible morphology of the peripheral vessel tree. Nonviral MCP-1 gene transfer significantly improved peripheral conductance (control 11.69+/-2.78%, 2 microg 23.81+/-2.81%, P<0.05 and 4 microg 23.36+/-3.1%, P<0.05; n=12 per group) as well as the ratio of peripheral over aortic blood pressure (control 0.64+/-0.03%, 2 microg 0.75+/-0.02%, P<0.05 and 4 mug 0.75+/-0.02%, P<0.05; n=12 per group) when compared to the untreated controls 2 weeks after occlusion. Thus, it could be demonstrated for the first time that in situ overexpression of MCP-1 following local nonviral gene transfer is a potential approach to improve peripheral collateralization.

No apoptotic deaths and different levels of inductions of inflammatory cytokines in alveolar macrophages infected with influenza viruses

Influenza viruses are reported to infect mainly the respiratory tract epithelium of hosts. Our studies in a pig model show that influenza A viruses infect alveolar macrophages that constitutively reside in the respiratory tract, without causing apoptosis. Tumor necrosis factor alpha was the inflammatory cytokine most highly induced in these macrophages. In vivo, alveolar macrophages infected with human H3N2 influenza virus showed greater expression of tumor necrosis factor alpha than did alveolar macrophages infected with human H1N1 influenza virus. Induction of specific inflammatory cytokine such as TNF-alpha is a polygenic trait that involves the HA and NA genes. Markedly elevated expression of tumor necrosis factor alpha may be responsible for the high mortality rate caused by H3N2 influenza virus infection in elderly patients.

Development of a macroarray to specifically analyze immunological gene expression in swine

DNA arrays are useful tools for simultaneously studying the expressions of a large number of genes. Herein, we describe the construction and the optimization of conditions for a low-density DNA macroarray specific for the porcine immune system. This specific DNA macroarray contains 63 gene products, including 20 cytokines, 11 chemokines, and 12 immunologically relevant receptors. It was constructed by designing gene-specific oligonucleotide primers from porcine sequences available in the EMBL or TIGR expressed sequence tag data bank and using primers from conserved regions of aligned sequences from other species for sequences unavailable for swine. Amplicons produced by reverse transcription-PCR were cloned, sequenced, and spotted onto nylon filters. A trial DNA array was first produced to optimize the intensity, specificity, and variability of signals from amplicons amplified with either gene-specific or universal primers. The DNA macroarray was then validated by comparing the gene expression profile of nonstimulated peripheral blood mononuclear cells (PBMCs) to that of phorbol 12-myristate 13-acetate and ionomycin (PMA-Iono)-stimulated PBMCs from three different animals over a 48-h time period. As already described for more conventional techniques, we showed that certain genes, such as those for CD40, gamma interferon, interleukin 2 (IL-2), the IL-2 receptor, and tumor necrosis factor alpha, were upregulated in PMA-Iono-stimulated PBMCs. A detailed analysis also indicated a downregulation of several genes which are expressed mainly by macrophages (IL-1, IL-8, AMCF-1, natural-resistance-associated macrophage protein, neutrophil chemotactic protein, DAP-12, and monocyte chemoattractant protein) in samples stimulated for 24 h with PMA-Iono compared to their levels of expression in control samples. These results indicate that the DNA macroarray that we constructed can be a useful tool for simultaneously monitoring the mRNA expression of immunologically relevant genes in different porcine samples.

Construction and application of a bovine immune-endocrine cDNA microarray

A variety of commercial DNA arrays specific for humans and rodents are widely available; however, microarrays containing well-characterized genes to study pathway-specific gene expression are not as accessible for domestic animals, such as cattle, sheep and pigs. Therefore, a small-scale application-targeted bovine immune-endocrine cDNA array was developed to evaluate genetic pathways involved in the immune-endocrine axis of cattle during periods of altered homeostasis provoked by physiological or environmental stressors, such as infection, vaccination or disease. For this purpose, 167 cDNA sequences corresponding to immune, endocrine and inflammatory response genes were collected and categorized. Positive controls included 5 housekeeping genes (glyceraldehydes-3-phosphate dehydrogenase, hypoxanthine phosphoribosyltransferase, ribosomal protein L19, beta-actin, beta2-microglobulin) and bovine genomic DNA. Negative controls were a bacterial gene (Rhodococcus equi 17-kDa virulence-associated protein) and a partial sequence of the plasmid pACYC177. In addition, RNA extracted from un-stimulated, as well as superantigen (Staphylococcus aureus enterotoxin-A, S. aureus Cowan Pansorbin Cells) and mitogen-stimulated (LPS, ConA) bovine blood leukocytes was mixed, reverse transcribed and PCR amplified using gene-specific primers. The endocrine-associated genes were amplified from cDNA derived from un-stimulated bovine hypothalamus, pituitary, adrenal and thyroid gland tissues. The array was constructed in 4 repeating grids of 180 duplicated spots by coupling the PCR amplified 213-630 bp gene fragments onto poly-l-lysine coated glass slides. The bovine immune-endocrine arrays were standardized and preliminary gene expression profiles generated using Cy3 and Cy5 labelled cDNA from un-stimulated and ConA (5 microg/ml) stimulated PBMC of 4 healthy Holstein cows (2-4 replicate arrays/cow) in a time course study. Mononuclear cell-derived cytokine and chemokine (IL-2, IL-1alpha, TNFalpha, IFN-gamma, TGFbeta-1, MCP-1, MCP-2 and MIP-3alpha) mRNA exhibited a repeatable and consistently low expression in un-stimulated cells and at least a two-fold increased expression following 6 and 24 h ConA stimulation as compared to 0 h un-stimulated controls. In contrast, expression of antigen presenting molecules, MHC-DR, MHC-DQ and MHC-DY, were consistently at least two-fold lower following 6 and 24 h ConA stimulation. The only endocrine gene with differential expression following ConA stimulation was prolactin. Additionally, due to the high level of genetic homology between ovine, swine and bovine genes, RNA similarly acquired from sheep and pigs was evaluated and similar gene expression patterns were noted. These data demonstrate that this application-targeted array containing a set of well characterized genes can be used to determine the relative gene expression corresponding to immune-endocrine responses of cattle and related species, sheep and pigs.

Neutrophil and small intestinal lymphocyte migration after Salmonella typhimurium infection: impact of fermentable fiber

OBJECTIVES

Formula-fed infants have more episodes of acute diarrhea and intestinal infection than do breast-fed infants. Nutrient additions to infant formula that could confer some of the immune benefits of breast milk to formula-fed infants are currently under investigation. This study examined the impact of enteral formulas supplemented with fermentable substrates on small intestinal lymphocyte and neutrophil migration in piglets infected with Salmonella typhimurium. Small intestinal proinflammatory cytokine messenger RNA abundance and in vitro lipopolysaccharide-stimulated interleukin-6 release in whole blood were assessed.

METHODS

Piglets were randomized to receive sow milk replacer formula supplemented with methylcellulose (control), soy polysaccharides (SPS) or fructooligosaccharides (FOS). On day 7, half of the piglets were infected with S. typhimurium. Intestinal lymphocyte, neutrophil and whole blood samples were obtained on day 14.

RESULTS

After infection, there was decreased lymphocyte migration in the control group but not in the SPS and FOS groups. The SPS group had greater neutrophil migration compared with the control and FOS groups, regardless of infection. Small intestinal abundance of proinflammatory cytokine messenger RNA was not significantly changed by either infection or diet. Blood from the FOS group challenged with lipopolysaccharide for 2 hours exhibited decreased interleukin-6 production compared with blood from the control and SPS groups, regardless of infection.

CONCLUSIONS

Supplementation of enteral formulas with SPS maintains the migratory function of small intestinal lymphocytes while increasing that of neutrophils.

Expression of inflammatory cytokines (TNF-alpha, IL-1, IL-6 and IL-8) in colon of pigs naturally infected with Salmonella typhimurium and S. choleraesuis

The expression of mRNA encoding tumour necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), IL-6 and IL-8 was studied, by in situ hybridization with a non-radioactive digoxigenin-labelled probe, in formalin-fixed, paraffin wax-embedded colonic tissue from pigs naturally infected with Salmonella typhimurium and S. choleraesuis. By in situ hybridization, a distinct positive signal for TNF-alpha, IL-1, IL-6 and IL-8 was detected in colon from all 12 infected pigs. Hybridization signals for all four inflammatory cytokines were detected primarily inflammatory cells infiltrating the lamina propria and submucosa. In comparison, expression of all four inflammatory cytokines was minimal in non-lesional colon of infected pigs and in normal colon from control pigs. The results suggest that these cytokines play an important role in the pathophysiological processes in porcine salmonellosis.

Leptin alters antibody isotype in the pig in vivo, but does not regulate cytokine expression or stimulate STAT3 signaling in peripheral blood monocytes in vitro1

Although leptin modulates immunological pathways in some species, the role of leptin as a regulator of immunocyte function in the pig has not been studied. Therefore, the primary objective of this study was to determine whether leptin influences specific immunocyte response variables in the pig in vivo or in vitro. Fifteen pigs (five pigs per treatment) were 1) injected with recombinant human leptin and allowed to consume feed ad libitum, 2) injected with vehicle and allowed to consume feed ad libitum, or 3) injected with vehicle and limit-fed to the intake of the leptin-injected group. All the pigs also were injected with the antigen, Limulus hemocyanin, on d 0 and 15 of the experiment. Exogenous leptin decreased (P < 0.05) daily feed intake and antigen-specific immunoglobulin (Ig) G1, but had no effect on lymphocyte proliferation or antigen-specific IgG2. In a second series of experiments, peripheral blood mononuclear cells (PBMC) were isolated from venous blood to determine the effect of stimulation with the polyclonal mitogen, concanavalin A (ConA), on the long form of the leptin receptor (Ob-Rl) mRNA abundance, and to determine whether leptin altered mitogen-induced proliferation, cytokine production, or signal transducer and activator of transcription 3 (STAT3) activation. Leptin had no effect on the proliferation of PBMC or on cytokine mRNA abundance or secretion. The abundance of Ob-Rl mRNA was decreased (P < 0.05) in response to stimulation with ConA. Constitutive STAT3 DNA binding was evident in mobility shift assays, but was not altered by either leptin or serum deprivation. These data indicate that leptin modifies antibody isotypes in the pig, and that Ob-Rl expression is downregulated in response to polyclonal mitogens in porcine PBMC. The constitutive activation of STAT3, coupled with the absence of leptin-inducible binding, indicates an alternative signaling pathway for leptin in pig PBMC.