Early immune response following Salmonella enterica subspecies enterica serovar Typhimurium infection in porcine jejunal gut loops

Study of the economic impact of cryptosporidiosis in calves after implementing good practices to manage the disease on dairy farms in Belgium, France, and the Netherlands

Cryptosporidium spp. are widespread parasitic protozoans causing enteric infections in humans and animals. The parasites cause neonatal diarrhoea in calves, leading to a high mortality rate in the first three weeks. Losses are significant for farmers, but the cost of cryptosporidiosis remains poorly documented. In the absence of a vaccine, only preventive measures are available to farmers to combat the infection. This study, conducted between 2018 and 2021, aimed to evaluate the economic impact of Cryptosporidium spp. on European dairy farms and monitor changes in costs after implementing disease management measures. First, a field survey was carried out and questionnaires administered to 57 farmers in Belgium, France, and the Netherlands. The aim of the survey was to assess the losses associated with the occurrence of diarrhoea in calves aged between 3 days and 3 weeks. The economic impact of diarrhoea was calculated based on mortality losses, health expenditures, and additional labour costs. To refine the cost estimation specifically for Cryptosporidium spp., stool samples were collected from 10 calves per farm. The prevalence of Cryptosporidium spp. was determined, and the economic impact of diarrhoea was adjusted accordingly. The assumption was made that a certain percentage of costs was attributed to cryptosporidiosis based on the prevalence. These protocols were repeated at the end of the study to observe changes in costs. In the three years, the cost of diarrhoea for the 28 farms that stayed in the panel all along the study improved from €140 in 2018 to €106 on average per diarrhoeic calf in 2021. With a stable prevalence at 40%, the cost of cryptosporidiosis per infected calf decreased from €60.62 to €45.91 in Belgium, from €43.83 to €32.14 in France, and from €58.24 to €39.48 in the Netherlands. This represented an average of €15 saved per infected calf. The methodology employed in this study did not allow us to conclude that the improvement is strictly due to the implementation of preventive measures. However, with 11 million calves raised in the Interreg 2 Seas area covered by the study, it provided valuable insights into the economic burden of Cryptosporidium spp.

Emerging mycotoxins induce hepatotoxicity in pigs' precision-cut liver slices and HepG2 cells

Emerging mycotoxins are currently gaining more attention due to their high frequency of contamination in foods and grains. However, most data available in the literature are in vitro, with few in vivo results that prevent establishing their regulation. Beauvericin (BEA), enniatins (ENNs), emodin (EMO), apicidin (API) and aurofusarin (AFN) are emerging mycotoxins frequently found contaminating food and there is growing interest in studying their impact on the liver, a key organ in the metabolization of these components. We used an ex vivo model of precision-cut liver slices (PCLS) to verify morphological and transcriptional changes after acute exposure (4 h) to these mycotoxins. The human liver cell line HepG2 was used for comparison purposes. Most of the emerging mycotoxins were cytotoxic to the cells, except for AFN. In cells, BEA and ENNs were able to increase the expression of genes related to transcription factors, inflammation, and hepatic metabolism. In the explants, only ENN B1 led to significant changes in the morphology and expression of a few genes. Overall, our results demonstrate that BEA, ENNs, and API have the potential to be hepatotoxic.

Immune-enhancing Effects of Chitosan-fermented Feed Additive on Broiler Chickens and Subsequent Protection Conferred against Experimental Infection with Salmonella Gallinarum

Benefits chitosan-fermented feed additives (CFFAs) particularly in the regulation of the immune system and antimicrobial activity. Therefore, we investigated the immune-enhancing and bacterial clearance effects of CFFA (fermented by Bacillus licheniformis) on broiler chickens Salmonella Gallinarum challenge. We administered 2% or 4% CFFA evaluated its immune-enhancing effects using several immunological experiments, including examination of lysozyme activity, lymphocyte proliferation, and expression of cytokines. We also evaluated the bacterial clearance effects of CFFA against S. Gallinarum. CFFA administration markedly enhanced lysozyme activity, lymphocyte proliferation, and the expression of interleukin (IL)-2, IL-12, tumor necrosis factor alpha, and interferon gamma in the spleen. In broilers challenged with S. Gallinarum, the clinical signs of S. Gallinarum infection and the number of viable bacterial colonies in the feces and tissues decreased in both CFFA groups. Therefore, CFFAs could be good candidates for feed additive to improve nonspecific immune responses and bacterial clearance.

Inflammatory Responses Induced by the Monophasic Variant of Salmonella Typhimurium in Pigs Play a Role in the High Shedder Phenotype and Fecal Microbiota Composition

Pigs infected with Salmonella may excrete large amounts of Salmonella, increasing the risk of spread of this pathogen in the food chain. Identifying Salmonella high shedder pigs is therefore required to mitigate this risk. We analyzed immune-associated markers and composition of the gut microbiota in specific-pathogen-free pigs presenting different shedding levels after an oral infection with Salmonella. Immune response was studied through total blood cell counts, production of anti-Salmonella antibodies and cytokines, and gene expression quantification. Total Salmonella shedding for each pig was estimated and hierarchical clustering was used to cluster pigs into high, intermediate, and low shedders. Gut microbiota compositions were assessed using 16S rRNA microbial community profiling. Comparisons were made between control and inoculated pigs, then between high and low shedders pigs. Prior to infection, high shedders had similar immunological profiles compared to low shedders. As soon as 1 day postinoculation (dpi), significant differences on the cytokine production level and on the expression level of several host genes related to a proinflammatory response were observed between high and low shedders. Infection with Salmonella induced an early and profound remodeling of the immune response in all pigs, but the intensity of the response was stronger in high shedders. In contrast, low shedders seroconverted earlier than high shedders. Just after induction of the proinflammatory response (at 2 dpi), some taxa of the fecal microbiota were specific to the shedding phenotypes. This was related to the enrichment of several functional pathways related to anaerobic respiration in high shedders. In conclusion, our data show that the immune response to Salmonella modifies the fecal microbiota and subsequently could be responsible for shedding phenotypes. Influencing the gut microbiota and reducing intestinal inflammation could be a strategy for preventing Salmonella high shedding in livestock. IMPORTANCE Salmonellosis remains the most frequent human foodborne zoonosis after campylobacteriosis and pork meat is considered one of the major sources of human foodborne infections. At the farm, host heterogeneity in pig infection is problematic. High Salmonella shedders contribute more significantly to the spread of this foodborne pathogen in the food chain. The identification of predictive biomarkers for high shedders could help to control Salmonella in pigs. The purpose of the present study was to investigate why some pigs become super shedders and others low shedders. We thus investigated the differences in the fecal microbial composition and the immune response in orally infected pigs presenting different Salmonella shedding patterns. Our data show that the proinflammatory response induced by S. Typhimurium at 1 dpi could be responsible for the modification of the fecal microbiota composition and functions observed mainly at 2 and 3 dpi and to the low and super shedder phenotypes.

Dietary supplementation with a complex of cinnamaldehyde, carvacrol, and thymol negatively affects the intestinal function in LPS-challenged piglets

Background

The effects of cinnamaldehyde, carvacrol and thymol complex (CCT) on the growth performance and intestinal function of piglets challenged with lipopolysaccharide (LPS) were determined. Colistin sulphate (CS) was as a positive control.

Method

Piglets (n = 24, 32 days of age) were allocated to four treatments: Control group (fed basal diet), LPS group (fed basal diet), CS+LPS group (fed basal diet + 50 mg/kg CS), and CCT+LPS group (fed basal diet + 50 mg/kg CCT).

Results

Results showed that diarrhea rates of piglets were significantly reduced by CCT and CS supplementation respectively. Further research showed that CS supplementation tended to improve the intestinal absorption function in LPS-challenged piglets. Moreover, CS supplementation significantly reduced the contents of cortisol in blood and malondialdehyde in the duodenum and the activities of inducible nitric oxide synthase in the duodenum and ileum and total nitric oxide synthase in the ileum in LPS-challenged piglets. CS supplementation significantly increased the activities of sucrase in the ileum and myeloperoxidase in the jejunum in LPS-challenged piglets. CS supplementation significantly alleviated the reduced mRNA levels of immune-related genes (IL-4, IL-6, IL-8, IL-10) in mesenteric lymph nodes and jejunum and mucosal growth-related genes (IGF-1, mTOR, ALP) in LPS-challenged piglets. These results suggested that CS supplementation improved the intestinal function in LPS-challenged piglets by improving intestinal oxidative stress, immune stress, and absorption and repair function. However, although CCT supplementation improved oxidative stress by reducing (p < 0.05) the content of malondialdehyde and the activity of nitric oxide synthase in the duodenum, CCT supplementation tended to aggravate the intestinal absorption dysfunction in LPS-challenged piglets. Furthermore, compared with the control and LPS groups, CCT supplementation remarkably elevated the content of prostaglandin in plasma and the mRNA levels of pro-inflammatory factor IL-6 in mesenteric lymph nodes and jejunum, and reduced the activity of maltase in the ileum in LPS-challenged piglets. These results suggested that CCT supplementation had a negative effect on intestinal function by altering intestinal immune stress response and reducing disaccharidase activity in LPS-challenged piglets.

Conclusions

Compared to CS, CCT supplementation exhibited a negative effect on intestinal function, suggesting whether CCT can be as an effective feed additive still needs further study.

Co-infection of porcine deltacoronavirus and porcine epidemic diarrhea virus induces early TRAF6-mediated NF-κB and IRF7 signaling pathways through TLRs

Porcine deltacoronavirus (PDCoV) and porcine epidemic diarrhea virus (PEDV) infect the small intestine and cause swine enteric coronavirus disease. The mucosal innate immune system is the first line of defense against viral infection. The modulatory effect of PDCoV and PEDV coinfection on antiviral signaling cascades of the intestinal mucosa has not been reported. Here, we investigate the gene expression levels of pattern recognition receptors, downstream inflammatory signaling pathway molecules, and associated cytokines on the intestinal mucosa of neonatal piglets either infected with a single- or co-infected with PDCoV and PEDV using real-time PCR. The results demonstrate that single-PEDV regulates the noncanonical NF-κB signaling pathway through RIG-I regulation. In contrast, single-PDCoV and PDCoV/PEDV coinfection regulate proinflammatory and regulatory cytokines through TRAF6-mediated canonical NF-κB and IRF7 signaling pathways through TLRs. Although PDCoV/PEDV coinfection demonstrated an earlier modulatory effect in these signaling pathways, the regulation of proinflammatory and regulatory cytokines was observed simultaneously during single viral infection. These results suggested that PDCoV/PEDV coinfection may have synergistic effects that lead to enhanced viral evasion of the mucosal innate immune response.

Cytokine expression by CD163+ monocytes in healthy and Actinobacillus pleuropneumoniae-infected pigs

Distinct monocyte subpopulations have been previously described in healthy pigs and pigs experimentally infected with Actinobacillus pleuropneumoniae (APP). The CD163+ subpopulation of bone marrow (BM), peripheral blood (PB) and lung monocytes was found to play an important role in the inflammatory process. The inflammation is accompanied by elevation of inflammatory cytokines. The aim of the study was to evaluate the contribution of CD163+ monocytes and macrophages to cytokine production during APP-induced lung inflammation. Cytokine production was assessed by flow cytometry (FC) and quantitative PCR (qPCR) in CD163+ monocytes and by qPCR, immunohistochemistry/fluorescence in lungs and tracheobronchial lymph nodes (TBLN). Despite the systemic inflammatory response after APP infection, BM and PB CD163+ monocytes did not express elevated levels of a wide range of cytokines compared to control pigs. In contrast, significant amounts of IL-1β, IL-6, IL-8 and TNF-α were produced in lung lesions and IL-1β in the TBLN. At the protein level, TNF-α was expressed by both CD163+ monocytes and macrophages in lung lesions, whereas IL-1β, IL-6 and IL-8 expression was found only in CD163+ monocytes; no CD163+ macrophages were found to produce these cytokines. Furthermore, the quantification of CD163+ monocytes expressing the two cytokines IL-1β and IL-8 that were most elevated was performed. In lung lesions, 36.5% IL-1β positive CD163+ monocytes but only 18.3% IL-8 positive CD163+ monocytes were found. In conclusion, PB and BM CD163+ monocytes do not appear to contribute to the elevated cytokine levels in plasma. On the other hand, CD163+ monocytes contribute to inflammatory cytokine expression, especially IL-1β at the site of inflammation during the inflammatory process.

Establishment of a Newborn Lamb Gut-Loop Model to Evaluate New Methods of Enteric Disease Control and Reduce Experimental Animal Use

Enteric infectious diseases are not all well controlled, which leads to animal suffering and sometimes death in the most severe cases, in addition to economic losses for farmers. Typical symptoms of enteric infections include watery diarrhea, stomach cramps or pain, dehydration, nausea, vomiting, fever and weight loss. Evaluation of new control methods against enteric infections requires the use of many animals. We aimed to develop a new method for an initial in vivo screen of promising compounds against neonatal diseases such as cryptosporidiosis while limiting experimental animal use. We therefore adapted an in vivo method of multiple consecutive but independent intestinal loops to newborn lambs delivered by cesarean section, in which endotoxin responsiveness is retained. This new method allowed for the screening of natural yeast fractions for their ability to stimulate immune responses and to limit early Cryptosporidium parvum development. This model may also be used to investigate host–pathogen interactions and immune responses in a neonatal controlled environment.

T-Cell Cytokine Response in Salmonella Typhimurium-Vaccinated versus Infected Pigs

Vaccination with the live attenuated vaccine Salmoporc is an effective measure to control Salmonella Typhimurium (STM) in affected swine populations. However, the cellular immune response evoked by the Salmoporc vaccine including differences in vaccinated pigs versus non-vaccinated pigs upon STM infection have not been characterized yet. To investigate this, tissue-derived porcine lymphocytes from different treatment groups (vaccination-only, vaccination and infection, infection-only, untreated controls) were stimulated in vitro with heat-inactivated STM and abundances of IFN-γ, TNF-α and/or IL-17A-producing T-cell subsets were compared across organs and treatment groups. Overall, our results show the induction of a strong CD4⁺ T-cell response after STM infection, both locally and systemically. Low-level induction of STM-specific cytokine-producing CD4⁺ T cells, notably for the IFN-γ/TNF-α co-producing phenotype, was detected after vaccination-only. Numerous significant contrasts in cytokine-producing T-cell phenotypes were observed after infection in vaccinated and infected versus infected-only animals. These results suggest that vaccine-induced STM-specific cytokine-producing CD4⁺ T cells contribute to local immunity in the gut and may limit the spread of STM to lymph nodes and systemic organs. Hence, our study provides insights into the underlying immune mechanisms that account for the efficacy of the Salmoporc vaccine.

Early socialization and environmental enrichment of lactating piglets affects the caecal microbiota and metabolomic response after weaning

The aim of this study was to determine the possible impact of early socialization and an enriched neonatal environment to improve adaptation of piglets to weaning. We hypothesized that changes in the microbiota colonization process and in their metabolic response and intestinal functionality could help the animals face weaning stress. A total of 48 sows and their litters were allotted into a control (CTR) or an enriched treatment (ENR), in which piglets from two adjacent pens were combined and enriched with toys. The pattern of caecal microbial colonization, the jejunal gene expression, the serum metabolome and the intestinal physiology of the piglets were assessed before (-2 d) and after weaning (+ 3d). A differential ordination of caecal microbiota was observed after weaning. Serum metabolome suggested a reduced energetic metabolism in ENR animals, as evidenced by shifts in triglycerides and fatty acids, VLDL/LDL and creatine regions. The TLR2 gene showed to be downregulated in the jejunum of ENR pigs after weaning. The integration of gene expression, metabolome and microbiota datasets confirmed that differences between barren and enriched neonatal environments were evident only after weaning. Our results suggest that improvements in adaptation to weaning could be mediated by a better response to the post-weaning stress.

Antimicrobial Resistance and Molecular Characterization of Class 1 Integron in Salmonella Isolates Recovered from Pig Farms in Chongqing, China

Salmonella is considered one of the leading causes for foodborne diseases in humans. Pork and its products contaminated with Salmonella are increasingly recognized as an important source of human salmonellosis. The aim of this study was to investigate the antimicrobial resistance and prevalence of integrons in Salmonella isolates from pig farms. In total, 92 of 724 (12.7%) samples were Salmonella-positive, including 64 (15.0%) from fecal samples, 27 (12.6%) from floor samples, 1 (4.5%) from water samples, and 0 from feed and air samples. These isolates showed the highest resistance to tetracycline (85.9%), followed by trimethoprim (67.4%), ampicillin (60.9%), and chloramphenicol (51.1%). In addition, 51 isolates carried the complete class 1 integron, most of which (42/51) harbored antibiotic resistance cassettes. A total of six gene cassettes including orfF, est-X, dfrA1+aadA1, aadA1, dfrA12+aadA2, and sat were identified, in which the most prevalent one was orfF (29.4%). Furthermore, all 19 class 1 integron-positive isolates harboring dfr genes showed resistance to trimethoprim (SXT), suggesting that the trimethoprim resistance gene (dfr) may contribute to the emergence of SXT resistance phenotype. Therefore, considering the significance of integrons and related resistance genes for public health, special measures should be taken to control Salmonella spp. on the pig farms and to prevent spread of integrons and associated resistance genes.

Vaccination and Infection of Swine With Salmonella Typhimurium Induces a Systemic and Local Multifunctional CD4+ T-Cell Response

The gram-negative facultative intracellular bacteria Salmonella Typhimurium (STM) often leads to subclinical infections in pigs, but can also cause severe enterocolitis in this species. Due to its high zoonotic potential, the pathogen is likewise dangerous for humans. Vaccination with a live attenuated STM strain (Salmoporc) is regarded as an effective method to control STM infections in affected pig herds. However, information on the cellular immune response of swine against STM is still scarce. In this study, we investigated the T-cell immune response in pigs that were vaccinated twice with Salmoporc followed by a challenge infection with a virulent STM strain. Blood- and organ-derived lymphocytes (spleen, tonsils, jejunal and ileocolic lymph nodes, jejunum, ileum) were stimulated in vitro with heat-inactivated STM. Subsequently, CD4⁺ T cells present in these cell preparations were analyzed for the production of IFN-γ, TNF-α, and IL-17A by flow cytometry and Boolean gating. Highest frequencies of STM-specific cytokine-producing CD4⁺ T cells were found in lamina propria lymphocytes of jejunum and ileum. Significant differences of the relative abundance of cytokine-producing phenotypes between control group and vaccinated + infected animals were detected in most organs, but dominated in gut and lymph node-residing CD4⁺ T cells. IL-17A producing CD4⁺ T cells dominated in gut and gut-draining lymph nodes, whereas IFN-γ/TNF-α co-producing CD4⁺ T cells were present in all locations. Additionally, the majority of cytokine-producing CD4⁺ T cells had a CD8α⁺CD27^- phenotype, indicative of a late effector or effector memory stage of differentiation. In summary, we show that Salmonella-specific multifunctional CD4⁺ T cells exist in vaccinated and infected pigs, dominate in the gut and most likely contribute to protective immunity against STM in the pig.

Salmonella enterica Serovar Typhimurium Temporally Modulates the Enteric Microbiota and Host Responses To Overcome Colonization Resistance in Swine

Salmonella enterica serovar Typhimurium is a prevalent incitant of enteritis in human beings and nonhuman animals. It has been proposed that host defense responses incited by Salmonella allow the bacterium to overcome colonization resistance. Piglets (n = 24) were orally inoculated with S. enterica serovar Typhimurium DT104 or buffer alone, and the host and microbial responses were temporally examined at the acute (2 days postinoculation [dpi]), subacute (6 dpi), and recovery (10 dpi) stages of salmonellosis. At the acute stage of disease, body temperatures were elevated, and feed consumption and weight gain were reduced. The densities of Salmonella associated with the gut mucosa decreased over time, with higher densities of the bacterium in the ileum and the large intestine. Moreover, substantive histopathological changes were observed as a function of time, with prominent epithelial injury and neutrophil infiltration observed at 2 dpi. Correspondingly, a variety of host metrics were temporally affected in piglets with salmonellosis (e.g., TNFα, IFNγ, PR39, βD2, iNOS, IL8, REGIIIγ). The enteric microbiota was characterized using culture-independent and -dependent methods in concert, and taxon- and location-specific changes to the microbiota were observed in infected piglets. Bacteroides spp. (e.g., Bacteroides uniformis, Bacteroides fragilis), Streptococcus spp. (e.g., Streptococcus gallolyticus), and various Gammaproteobacteria were highly associated with inflamed tissues, while bacteria within the Ruminococcaceae and Veillonellaceae families were mainly associated with healthy mucosae. In conclusion, the study findings showed that S Typhimurium incited temporal and spatial modifications to the swine autochthonous microbiota, and to host defense responses, that were consistent with overcoming colonization resistance to incite salmonellosis in swine.IMPORTANCE Limited information is available on host and enteric microbiota responses incited by Salmonella enterica serovar Typhimurium in swine and on possible mechanisms by which the bacterium overcomes colonization resistance to incite salmonellosis. Temporal characterization of a variety of host metrics in piglets (e.g., physiological, histopathological, and immunological) showed the importance of studying the progression of salmonellosis. A number of host responses integrally associated with disease development were identified. Utilization of next-generation sequence analysis to characterize the enteric microbiota was found to lack sufficient resolution; however, culture-dependent and -independent methods in combination identified taxon- and location-specific changes to bacterial communities in infected piglets. The study identified bacterial and host responses associated with salmonellosis, which will be beneficial in understanding colonization resistance and in the development of effective alternatives to antibiotics to mitigate salmonellosis.

Porcine Reproductive and Respiratory Syndrome Virus Interferes with Swine Influenza A Virus Infection of Epithelial Cells

Respiratory infections are still a major concern in pigs. Amongst the involved viruses, the porcine reproductive and respiratory syndrome virus (PRRSV) and the swine influenza type A virus (swIAV) have a major impact. These viruses frequently encounter and dual infections are reported. We analyzed here the molecular interactions between viruses and porcine tracheal epithelial cells as well as lung tissue. PRRSV-1 species do not infect porcine respiratory epithelial cells. However, PRRSV-1, when inoculated simultaneously or shortly before swIAV, was able to inhibit swIAV H1N2 infection, modulate the interferon response and alter signaling protein phosphorylations (ERK, AKT, AMPK, and JAK2), in our conditions. SwIAV inhibition was also observed, although at a lower level, by inactivated PRRSV-1, whereas acid wash treatment inactivating non-penetrated viruses suppressed the interference effect. PRRSV-1 and swIAV may interact at several stages, before their attachment to the cells, when they attach to their receptors, and later on. In conclusion, we showed for the first time that PRRSV can alter the relation between swIAV and its main target cells, opening the doors to further studies on the interplay between viruses. Consequences of these peculiar interactions on viral infections and vaccinations using modified live vaccines require further investigations.

Maternal Supplementation of Food Ingredient (Prebiotic) or Food Contaminant (Mycotoxin) Influences Mucosal Immune System in Piglets

The early life period is crucial for the maturation of the intestinal barrier, its immune system, and a life-long beneficial host-microbiota interaction. The study aims to assess the impact of a beneficial dietary (short-chain fructooligosaccharides, scFOS) supplementation vs. a detrimental dietary environment (such as mycotoxin deoxynivalenol, DON) on offspring intestinal immune system developmental profiles. Sows were given scFOS-supplemented or DON-contaminated diets during the last 4 weeks of gestation, whereas force-feeding piglets with DON was performed during the first week of offspring life. Intestinal antigen-presenting cell (APC) subset frequency was analyzed by flow cytometry in the Peyer's patches and in lamina propria and the responsiveness of intestinal explants to toll-like receptor (TLR) ligands was performed using ELISA and qRT-PCR from post-natal day (PND) 10 until PND90. Perinatal exposure with scFOS did not affect the ontogenesis of APC. While it early induced inflammatory responses in piglets, scFOS further promoted the T regulatory response after TLR activation. Sow and piglet DON contamination decreased CD16+ MHCII+ APC at PND10 in lamina propria associated with IFNγ inflammation and impairment of Treg response. Our study demonstrated that maternal prebiotic supplementation and mycotoxin contamination can modulate the mucosal immune system responsiveness of offspring through different pathways.

Assessment of Immunological Response and Impacts on Fertility Following Intrauterine Vaccination Delivered to Swine in an Artificial Insemination Dose

To protect the health of sows and gilts, significant investments are directed toward the development of vaccines against infectious agents that impact reproduction. We developed an intrauterine vaccine that can be delivered with semen during artificial insemination to induce mucosal immunity in the reproductive tract. An in vitro culture of uterine epithelial cells was used to select an adjuvant combination capable of recruiting antigen-presenting cells into the uterus. Adjuvant polyinosinic:polycytidylic acid (poly I:C), alone or in combination, induced expression of interferon gamma, tumor necrosis factor alpha, and select chemokines. A combination adjuvant consisting of poly I:C, host defense peptide and polyphosphazene (Triple Adjuvant; TriAdj), which previously was shown to induce robust mucosal and systemic humoral immunity when administered to the uterus in rabbits, was combined with boar semen to evaluate changes in localized gene expression and cellular recruitment, in vivo. Sows bred with semen plus TriAdj had decreased γδ T cells and monocytes in blood, however, no corresponding increase in the number of monocytes and macrophages was detected in the endometrium. Compared to sows bred with semen alone, sows bred with semen plus TriAdj showed increased CCL2 gene expression in the epithelial layer. These data suggest that the adjuvants may further augment a local immune response and, therefore, may be suitable for use in an intrauterine vaccine. When inactivated porcine parvovirus (PPV) formulated with the TriAdj was administered to the pig uterus during estrus along with semen, we observed induction of PPV antibodies in serum but only when the pigs were already primed with parenteral PPV vaccines. Recombinant protein vaccines and inactivated PPV vaccines administered to the pig uterus during breeding as a primary vaccine alone failed to induce significant humoral immunity. More trials need to be performed to clarify whether repeated intrauterine vaccination can trigger strong humoral immunity or whether the primary vaccine needs to be administered via a systemic route to promote a mucosal and systemic immune response.

Reduced toxicity of 3-epi-deoxynivalenol and de-epoxy-deoxynivalenol through deoxynivalenol bacterial biotransformation: In vivo analysis in piglets

Ingestion of deoxynivalenol (DON), one of the most common mycotoxin contaminants of cereals, leads to adverse effects for animal and human health. Bacterial biotransformation is a strategy to mitigate the toxicity of this mycotoxin. The present study aims to evaluate the toxicity of two bacterial biotranformation products of DON: 3-epi-deoxynivalenol (3-epi-DON) and de-epoxy-deoxynivalenol (DOM-1) through zootechnical, hematological, histological and immunological assays. Twenty-four 4-weeks-old piglets received a control diet or a diet contaminated with 3 mg kg^-1 DON, DOM-1, or 3-epi-DON for 7 days. Sample tissues were collected for histomorphometrical analysis, expression of cytokines and cell protein junctions. The zootechnical and hematological parameters were not modulated by any treatment. Ingestion of DON induced histological alterations in the intestine, liver and lymphoid organs, as well as an overexpression of pro-inflammatory cytokines, E-cadherin and occludin. These changes were not observed in piglets receiving the DOM-1 and 3-epi-DON contaminated diets. Pigs fed 3-epi-DON contaminated diet showed an increase in IgM levels in comparison with other diets, while no change was observed in IgA and IgG levels among the diets. Our results indicate that DOM-1 and 3-epi-DON are not toxic for piglets; thus bacterial biotransformation seems to be a sustainable alternative to reduce mycotoxin toxicity.

Microarray analysis reveals the inhibition of intestinal expression of nutrient transporters in piglets infected with porcine epidemic diarrhea virus

Porcine epidemic diarrhea virus (PEDV) infection can induce intestinal dysfunction, resulting in severe diarrhea and even death, but the mode of action underlying these viral effects remains unclear. This study determined the effects of PEDV infection on intestinal absorption and the expression of genes for nutrient transporters via biochemical tests and microarray analysis. Sixteen 7-day-old healthy piglets fed a milk replacer were randomly allocated to one of two groups. After 5-day adaption, piglets (n = 8/group) were orally administrated with either sterile saline or PEDV (the strain from Yunnan province) at 10^4.5 TCID₅₀ (50% tissue culture infectious dose) per pig. All pigs were orally infused D-xylose (0.1 g/kg BW) on day 5 post PEDV or saline administration. One hour later, jugular vein blood samples as well as intestinal samples were collected for further analysis. In comparison with the control group, PEDV infection increased diarrhea incidence, blood diamine oxidase activity, and iFABP level, while reducing growth and plasma D-xylose concentration in piglets. Moreover, PEDV infection altered plasma and jejunal amino acid profiles, and decreased the expression of aquaporins and amino acid transporters (L-type amino acid transporter 1, sodium-independent amino acid transporter, B(°^,+)-type amino acid transport protein, sodium-dependent neutral amino acid transporter 1, sodium-dependent glutamate/aspartate transporter 3, and peptide transporter (1), lipid transport and metabolism-related genes (lipoprotein lipase, apolipoprotein A1, apolipoprotein A4, apolipoprotein C2, solute carrier family 27 member 2, solute carrier family 27 member 4, fatty acid synthase, and long-chain acyl-CoA synthetase (3), and glucose transport genes (glucose transporter-2 and insulin receptor) in the jejunum. However, PEDV administration increased mRNA levels for phosphoenolpyruvate carboxykinase 1, argininosuccinate synthase 1, sodium/glucose co-transporter-1, and cystic fibrosis transmembrane conductance regulator in the jejunum. Collectively, these comprehensive results indicate that PEDV infection induces intestinal injury and inhibits the expression of genes encoding for nutrient transporters.

IPEC-1 variable immune response to different serovars of Salmonella enterica subsp. enterica

Salmonella is a genus of Gram-negative bacteria in the Enterobacteriaceae family causing various illnesses. The ability of the different serovars of Salmonella enterica subsp. enterica to infect a host and to induce pathology relies in part on their cellular and molecular interactions with the intestinal epithelium. In the current study, an in vitro approach using non-polarized or polarized IPEC-1 porcine intestinal epithelial cells were used in order to assess the relation between adhesion, invasion, and induction of the immune response as a function of the serotype of Salmonella. Five serovars, Choleraesuis (host-adapted), Typhimurium (ubiquitous), Typhisuis (host-restricted), which are relevant for pig infection, and Dublin and Gallinarum, which are host-restricted or host-adapted, were studied. A strong variation was observed in the percentages of adhesion and invasion amongst the S. enterica serovars used to interact with the non-polarized and polarized cells. Subsequently, differences were identified between serovars in terms of immune response induced. Serovars Typhimurium and Typhisuis induced a strong innate immune response four and half hours after the beginning of cell stimulation while Choleraesuis, Gallinarum, and Dublin did not. A strong inflammatory response could limit the spread of the porcine serovars to the gut while, with a weak response, bacteria may not be constrained by the immune response enabling severe systemic diseases. Different repertoires of adhesion factors and of secreted protein effectors between Salmonella serovars interacting with IPEC-1 cells probably explains the differences in their early pathogenic behaviours.

Proinflammatory Cytokine Changes in Bronchoalveolar Lavage Fluid Cells Isolated from Pigs Infected Solely with Porcine Reproductive and Respiratory Syndrome Virus or Co-infected with Swine Influenza Virus

Introduction

The study evaluated the patterns of local innate immune response in bronchoalveolar lavage fluid (BALF) cells of pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV) alone or co-infected with swine influenza virus (SIV).

Material and Methods

The study was performed on 26 seven-week-old pigs in three groups: PRRSV-infected (n = 11), PRRSV and SIV-infected (n = 11), and control (n = 4). BALF was collected post euthanasia at 2 and 4 dpi (three piglets per inoculated group) and at 21 dpi (all remaining pigs). Expression of IFN-α, IFN-γ, IL-1β, IL-6, IL-8, and IL-10 mRNA was quantified in BALF cells. PRRSV RNA was quantified in BALF samples using a commercial real-time RT-PCR kit.

Results

The three cytokines IFN-α, IFN-γ, and IL-1β presented significant expression changes in all experimental pigs. In PRRSV-infected animals IL-8 also did, but in co-infected subjects IL-6 and IL-10 were the additional upregulated cytokines. The highest number of differentially expressed genes was observed at 4 dpi, and significant differences in cytokine gene expression did not occur between the experimental groups at any other time point. The mean PRRSV load in the BALF of PRRSV-infected pigs was higher than that of co-infected pigs at each time point, having statistical significance only at 4 dpi.

Conclusion

The results of the study indicate that infection with PRRSV alone as well as with SIV interferes with innate and adaptive immune response in the infected host. They also showed that co-infection demonstrates additive effects on IL-6 and IL-10 mRNA expression levels.

Neonatal Exposure to Amoxicillin Alters Long-Term Immune Response Despite Transient Effects on Gut-Microbiota in Piglets

Antibiotic exposure during neonatal development may result in transient or persistent alterations of key microbes that are vital for normal development of local and systemic immunity, potentially impairing immune competence later in life. To further elucidate the relationship between antibiotic exposure and immune development, newborn pigs were exposed to a therapeutic pediatric dose (30 mg/kg/day) of amoxicillin (AB) or placebo (PL) from post-natal day (PND) 0–14. Subsequently, immune cell phenotype, microbial composition, and immune response to an intraperitoneal (IP) challenge with Salmonella enterica serovar Typhimurium were evaluated. AB exposure caused significant changes in fecal microbial composition on PND 3 (P = 0.025). This stemmed from a 2-fold increase in Enterobacteriaceae with live cecal coliforms on PND 7 indicating at 10-fold increase (P = 0.036). Alterations in microbial composition were transient, and successional patterns were normalizing by PND 14 (P = 0.693). Differences in PBMC (peripheral blood mononuclear cell) immune cell subtypes were detected, with the percentage of CD3⁺CD4⁺ T cells among the broader T cell population (CD3⁺CD4⁺/CD3⁺) being significantly higher (P = 0.031) in AB pigs and the numbers of CD4+CD45RA+ (naïve) T cells per liter of blood were lower on PND 21 in AB pigs (P = 0.036). Meanwhile, PBMCs from AB pigs produced significantly more IFNγ upon stimulation with a T-cell mitogen on PND 21 and 49 (P = 0.021). When AB pigs were challenged with heat-killed Salmonella (IP) on PND 49, IFNγ gene expression in peripheral blood was upregulated compared to those treated with PL (P = 0.043). Additionally, AB pigs showed stronger activation among neutrophils infiltrating the peritoneal cavity after in vivo immune challenge, based on higher levels of NF-κB nuclear translocation (P = 0.001). Overall, our results indicate that early life treatment with a therapeutically relevant dose of a commonly prescribed antibiotic has a programming effect on the immune system. Despite antibiotics only causing a transient disruption in gut-associated microbial communities, implications were long-term, with antibiotic treated pigs mounting an upregulated response to an immune challenge. This research adds to the growing body of evidence indicating adverse immune outcomes of early life antibiotic exposures.

Colonization of Germ-Free Piglets with Commensal Lactobacillus amylovorus, Lactobacillus mucosae, and Probiotic E. coli Nissle 1917 and Their Interference with Salmonella Typhimurium

Non-typhoid Salmonellae are worldwide spread food-borne pathogens that cause diarrhea in humans and animals. Their multi-drug resistances require alternative ways to combat this enteric pathogen. Mono-colonization of a gnotobiotic piglet gastrointestinal tract with commensal lactobacilli Lactobacillus amylovorus and Lactobacillus mucosae and with probiotic E. coli Nissle 1917 and their interference with S. Typhimurium infection was compared. The impact of bacteria and possible protection against infection with Salmonella were evaluated by clinical signs, bacterial translocation, intestinal histology, mRNA expression of villin, claudin-1, claudin-2, and occludin in the ileum and colon, and local intestinal and systemic levels of inflammatory cytokines IL-8, TNF-α, and IL-10. Both lactobacilli colonized the gastrointestinal tract in approximately 100× lower density compare to E. coli Nissle and S. Typhimurium. Neither L. amylovorus nor L. mucosae suppressed the inflammatory reaction caused by the 24 h infection with S. Typhimurium. In contrast, probiotic E. coli Nissle 1917 was able to suppress clinical signs, histopathological changes, the transcriptions of the proteins, and the inductions of the inflammatory cytokines. Future studies are needed to determine whether prebiotic support of the growth of lactobacilli and multistrain lactobacilli inoculum could show higher protective effects.

Corn-derived alpha-D-glucan nanoparticles as adjuvant for intramuscular and intranasal immunization in pigs

Adjuvant potential of positively charged corn-derived nanoparticles (Nano-11) was earlier revealed in mice. We evaluated its adjuvant role to electrostatically adsorbed inactivated/killed swine influenza virus antigen (KAg) (Nano-11 + KAg) in pigs. Nano-11 facilitated the uptake of KAg by antigen presenting cells and induced secretion of proinflammatory cytokines. In pigs vaccinated by an intranasal mist containing Nano-11 + KAg, expression of T-helper 1 and T-helper 2 transcription factors and secretion of cross-reactive influenza antigen-specific mucosal IgA in the nasal cavity were observed. The enhanced frequencies of IFN-γ positive T-helper and cytotoxic T-cells in Nano-11 + KAg-vaccinates after heterologous virus challenge were also observed. Clinically, slightly reduced influenza signs and pneumonic lesions, with mild reduction in virus load in the respiratory tract of vaccinates were observed. In pigs immunized with Nano-11 adsorbed ovalbumin administered by intramuscular (IM) route, enhanced IgG1 and IgG2 antibodies were detected in serum. Thus, Nano-11 vaccine delivery system confers adjuvant effect in pigs.

Regulators of Salmonella-host interaction identified by peripheral blood transcriptome profiling: roles of TGFB1 and TRP53 in intracellular Salmonella replication in pigs

Peripheral blood transcriptome is an important intermediate data source for investigating the mechanism of Salmonella invasion, proliferation, and transmission. We challenged 4-week old piglets with Salmonella enterica serovar Typhimurium LT2 and investigated the peripheral blood gene expression profile before treatment (d0) and at 2 and 7 days post-inoculation (dpi) using deep sequencing. Regulator pathways were first predicted in silico and validated by wet-lab experiments. In total, 1255, 765, and 853 genes were differentially expressed between 2 dpi/d0, 7 dpi/d0, and 7 dpi/2 dpi, respectively. Additionally, 1333 genes showed a time effect during the investigated Salmonella infection period. Clustering analysis showed that the differentially expressed genes fell into six distinct expression clusters. Pathway annotation of these gene clusters showed that the innate immune system was first significantly upregulated at 2 dpi and then attenuated at 7 dpi. Toll-like receptor cascades, MyD88 cascade, phagosome pathway, cytokine signaling pathway, and lysosome pathway showed a similar expression pattern. Interestingly, we found that the ribosome pathway was significantly inhibited at 2 and 7 dpi. Gene expression regulation network enrichment analysis identified several candidate factors controlling the expression clusters. Further in vitro study showed that TGFB1 can inhibit Salmonella replication whereas TRP53 can promote Salmonella replication in porcine peripheral blood mononuclear cells and murine macrophages. These results provide new insights into the molecular mechanism of Salmonella-host interactions and clues for the genetic improvement of Salmonella infection resistance in pigs.

Colonization of preterm gnotobiotic piglets with probiotic Lactobacillus rhamnosus GG and its interference with Salmonella Typhimurium

A balanced microbiota of the gastrointestinal tract (GIT) is a prerequisite for a healthy host. The GIT microbiota in preterm infants is determined by the method of delivery and nutrition. Probiotics can improve the GIT microbiota balance and suitable animal models are required to verify their harmlessness. Preterm gnotobiotic piglets were colonized with Lactobacillus rhamnosus GG (LGG) to evaluate its safety and possible protective action against infection with an enteric pathogen, Salmonella Typhimurium (ST). Clinical signs (anorexia, somnolence, fever and diarrhea), bacterial interference and translocation, intestinal histopathology, transcriptions of claudin-1, occludin and interferon (IFN)-γ, intestinal and systemic protein levels of interleukin (IL)-8, IL-12/23 p40 and IFN-γ were compared among (i) germ-free, (ii) LGG-colonized, (iii) ST-infected and (iv) LGG-colonized and subsequently ST-infected piglets for 24 h. Both LGG and ST-colonized the GIT; LGG translocated in some cases into mesenteric lymph nodes and the spleen but did not cause bacteremia and clinical changes. ST caused clinical signs of gastroenteritis, translocated into mesenteric lymph nodes, the spleen, liver and blood, increased claudin-1 and IFN-γ transcriptions, but decreased occludin transcription and increased local and systemic levels of IL-8 and IL-12/23 p40. Previous colonization with LGG reduced ST colonization in the jejunum and translocation into the liver, spleen and blood. It partially ameliorated histopathological changes in the intestine, reduced IL-8 levels in the jejunum and plasma and IL-12/23 p40 in the jejunum. The preterm gnotobiotic piglet model of the vulnerable preterm immunocompromised infant is useful to verify the safety of probiotics and evaluate their protective effect.

Distribution and Antimicrobial Resistance of Salmonella Isolated from Pigs with Diarrhea in China

Salmonella can cause enteric diseases in humans and a wide range of animals, and even outbreaks of foodborne illness. The aim of this study was to investigate the frequency and distribution of serovars, and antimicrobial resistance in Salmonella isolates from pigs with diarrhea in 26 provinces in China from 2014 to 2016. A total of 104 Salmonella isolates were identified and the dominant serovar was S. 4,[5],12:i:- (53.9%). All Salmonella isolates were resistant to trimethoprim-sulfamethoxazole, and many were resistant to ampicillin (80.8%) and tetracycline (76.9%). Among 104 Salmonella isolates, aac(6')-Ib-cr was the dominant plasmid-mediated quinolone resistance gene (80.8%), followed by qnrS (47.1%). The pulsed-field gel electrophoresis results suggest that the Salmonella isolates from different regions were genetically diverse, and ST34 was the most prevalent. S. 4,[5],12:i:- isolates is the widespread presence of heavy metal tolerance genes. The fact that the same sequence types were found in different regions and the high similarity coefficient of S. 4,[5],12:i:- isolates from different regions indicate the clonal expansion of the isolates, and the isolates carried various antimicrobial resistance genes. The multidrug resistant Salmonella can be widely detected in pigs, which will present a challenge for farm husbandry.

A Ligated Intestinal Loop Model in Anesthetized Specific Pathogen Free Chickens to Study Clostridium Perfringens Virulence

Necrotic enteritis was studied in chickens using various in vivo infection models. Most of these use a combination of predisposing factors, such as coccidiosis and diet, with gavage or administration via the feed using Clostridium perfringens. In these models, the comparison of multiple C. perfringens strains for virulence studies requires a large number of hosts to obtain significant results. Mortality during the course of the study can be high depending on the experimental model, hence raising ethical concerns regarding animal welfare in research. The development of new infection models requiring fewer animals to study pathogenesis, yet providing statistically significant and valid results, is important in reducing animal use in research. Intestinal ligated loop models have been used to study clostridial infections in various species such as mice, rabbits and calves. Following surgical procedures to create ligated loop segments, C. perfringens strains are injected directly into the loops to establish a close contact between the bacteria and the intestinal mucosa. Samples of the small intestine and luminal contents are taken at the termination of the procedures after a few hours. Multiple bacterial strains can be inoculated in each animal, hence reducing the number of required subjects in the experiments. Also, procedures are performed under general anesthesia to reduce animal pain. In chickens, this model would be more appropriate than oral administration to compare C. perfringens strain pathogenicity because fewer animals are needed, no predisposing factors are required to induce the disease, and pain is controlled by analgesics. The intestinal ligated loop model is poorly described in chickens and standardization is essential for its optimal use. This manuscript provides all the necessary steps to create numerous intestinal ligated loops in chickens and brings information on the critical points to obtain valid results.

Antibody and cytokine response to Cystoisospora suis infections in immune-competent young pigs

Background

To date, investigations on the immune response to Cystoisospora suis infections focused on suckling piglets, the age group clinically most affected. Actively immunizing piglets is unfeasible due to their immature immune system and the typically early infection in the first days after birth. Therefore, understanding and possibly enhancing the immune response of immune-competent animals is the prerequisite to develop a passive immunization strategy for piglets which currently rely on very limited treatment options.

Methods

To investigate antibody and cytokine responses of immune-competent animals and the impact of the oral immunization protocol on their immune response, growers with unknown previous exposure to C. suis (10–11 weeks-old) were infected one or three times with different doses (600 and 6000 or 200 and 2000, respectively) of C. suis oocysts, and compared to uninfected controls. Oocyst excretion was evaluated, and blood and intestinal mucus antibody titers were determined by IFAT. Systemic production of Th1, Th2, inflammatory and regulatory cytokines was determined in different immune compartments at mRNA and (after stimulation with a recombinant merozoite-protein) at protein level by PCR and multiplex fluorescent immunoassay, respectively.

Results

Infection generated significantly increased serum IgA and IgG levels against C. suis sporozoites and merozoites, irrespective of infection mode, with IgG against merozoites showing the strongest increase. No clinical signs and only occasional excretion were observed. The systemic cytokine response to C. suis was only weak. Nonetheless, in white blood cells, IL-4, IL-6 and IL-10 mRNA-levels significantly increased after infection, whereas IFN-ɣ, IL-2 and TGF-β expression tended to decrease. In mesenteric lymph nodes (MLN), IL-10 and TNF-α levels were elevated while splenic cytokine expression was unaltered upon infection. Stimulated MLN-derived lymphocytes from infected pigs produced slightly more IL-12 and less IFN-α than controls.

Conclusions

An infection and a subsequent systemic immune response can be induced in immune-competent animals by all evaluated infection models and growers can be used as models to mimic sow immunizations. The immune response to C. suis, although mild and with considerable variation in cytokine expression, was characterized by a Th2-associated and regulatory cytokine profile and antibody production. However, none of the parameters clearly stood out as a potential marker associated with protection. Antibody titers were significantly positively related with oocyst excretion and might thus serve as correlates for parasite replication or severity of infection.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2974-6) contains supplementary material, which is available to authorized users.

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.

In Vitro Transcriptome Response to a Mixture of Lactobacilli Strains in Intestinal Porcine Epithelial Cell Line

Background: Food and feed supplements containing microorganisms with probiotic potential are of increasing interest due to their healthy promoting effect on human and animals. Their mechanism of action is still unknown. Using a microarray approach, the aim of this study was to investigate the differences in genome-wide gene expression induced by a mixture of three Lactobacillus strains (L. rhamnosus, L. plantarum, and L. paracasei) in intestinal porcine epithelial cells (IPEC-1) and to identify the genes and pathways involved in intestinal barrier functions. Methods: Undifferentiated IPEC-1 cells seeded at a density of 2.0 × 10⁵/mL in 24-wells culture plates were cultivated at 37 °C and 5% CO₂ until they reached confluence (2–3 days). Confluent cells monolayer were then cultivated with 1 mL of fresh lactobacilli (LB) mixture suspension prepared for a concentration of approximately 3.3 × 10⁷ CFU/mL for each strain (1 × 10⁸ CFU/mL in total) for 3 h and analyzed by microarray using Gene Spring GX v.11.5. Results: The functional analysis showed that 1811 of the genes modulated by LB treatment are involved in signaling (95% up-regulation, 121 genes with a fold change higher than 10). The most enhanced expression was registered for AXIN2 (axis inhibition protein 2-AXIN2) gene (13.93 Fc, p = 0.043), a negative regulator of β-catenin with a key role in human cancer. LB affected the cellular proliferation by increasing 10 times (Fc) the NF1 gene encoding for the neurofibromin protein, a tumor suppressor that prevent cells from uncontrolled proliferation. The induction of genes like serpin peptidase inhibitor, clade A member 3 (SERPINA 3), interleukin-20 (IL-20), oncostatin M(OSM), granulocyte-macrophage colony-stimulating factor (GM-CSF), and the suppression of chemokine (C-X-C motif) ligand 2/macrophage inflammatory protein 2-alpha (CXCL-2/MIP-2), regulator of G-protein signaling 2 (RGS2), and of pro-inflammatory interleukin-18 (IL-18) genes highlights the protective role of lactobacilli in epithelial barrier function against inflammation and in the activation of immune response. Conclusion: Gene overexpression was the predominant effect produced by lactobacilli treatment in IPEC-1 cells, genes related to signaling pathways being the most affected. The protective role of lactobacilli in epithelial barrier function against inflammation and in the activation of immune response was also noticed.

Immunome differences between porcine ileal and jejunal Peyer's patches revealed by global transcriptome sequencing of gut-associated lymphoid tissues

The epithelium of the intestinal mucosa and the gut-associated lymphoid tissues (GALT) constitute an essential physical and immunological barrier against pathogens. In order to study the specificities of the GALT transcriptome in pigs, we compared the transcriptome profiles of jejunal and ileal Peyer’s patches (PPs), mesenteric lymph nodes (MLNs) and peripheral blood (PB) of four male piglets by RNA-Seq. We identified 1,103 differentially expressed (DE) genes between ileal PPs (IPPs) and jejunal PPs (JPPs), and six times more DE genes between PPs and MLNs. The master regulator genes FOXP3, GATA3, STAT4, TBX21 and RORC were less expressed in IPPs compared to JPPs, whereas the transcription factor BCL6 was found more expressed in IPPs. In comparison between IPPs and JPPs, our analyses revealed predominant differential expression related to the differentiation of T cells into Th1, Th2, Th17 and iTreg in JPPs. Our results were consistent with previous reports regarding a higher T/B cells ratio in JPPs compared to IPPs. We found antisense transcription for respectively 24%, 22% and 14% of the transcripts detected in MLNs, PPs and PB, and significant positive correlations between PB and GALT transcriptomes. Allele-specific expression analyses revealed both shared and tissue-specific cis-genetic control of gene expression.

Expression of pattern recognition receptors in porcine uterine epithelial cells in vivo and in culture

Preservation of a pathogen free uterine environment is critical for maintaining healthy swine herds with high reproductive performance. Considering that uterine epithelial cells are the most numerous and thus likely point of cellular contact for pathogens in the uterus, we hypothesize that these cells may be critical for activating the immune system to clear uterine infections. Although uterine epithelial cells have not been well characterized in pigs, studies in several other species have shown that these cells express several pattern recognition receptors (PRR) and thus may act as sentinels for the uterine immune response. To characterize PRR expression in the porcine uterine epithelia, we used laser-capture microdissection to isolate epithelial cells lining the porcine uterus to quantify in vivo mRNA expression levels for select PRRs. As well, primary uterine epithelial cells (UECs) were isolated, cultured, polarized and PRR expression was quantified. Immunohistofluorescence and immunofluorescence were used to determine subcellular localization of TLR3, TLR4 and TLR9 in both uterine tissue and in polarized primary UECs. Finally, polarized primary UECs were stimulated with ligands for TLR3, TLR4, TLR9 and NOD2 to determine their functional innate immune response. Uterine epithelial cells (in vivo and in vitro) were shown to express TLR1-7, TLR9, NOD1, NOD2, NLRP3, NLRP6, NLRX1, RIG1, MDA5 and LGP2. Subcellular localization of in vivo and polarized primary UECs exhibited TLR3 and TLR9 localized to the apical cell surface whereas TLR4 was localized to the intracellular space. Polarized primary UECs stimulated with TLR3, TLR4 and TLR9 ligands showed induced secretion of IL-6, IL-13 and IL-10, respectively indicating that these receptors were functional. These results indicate that pig uterine epithelial cells are functional innate immune cells that may act as sentinels to protect against uterine infection.

Dietary supplementation with an amino acid blend enhances intestinal function in piglets

The traditionally classified nutritionally non-essential amino acids are now known to be insufficiently synthesized for maximal growth and optimal health in piglets. This study determined the effects of dietary supplementation with an amino acid blend (AAB; glutamate:glutamine:glycine:arginine:N-acetylcysteine = 5:2:2:1:0.5) on piglet growth performance and intestinal functions. Sixteen piglets (24-day-old) were randomly assigned to a corn and soybean meal-based diet supplemented with 0.99% alanine (isonitrogenous control) or 1% AAB. On day 20 of the trial, blood and intestinal tissue samples were obtained from piglets. Compared with the control, AAB supplementation reduced (P < 0.05) diarrhoea incidence; plasma alanine aminotransferase and diamine oxidase activities; intestinal concentrations of hydrogen peroxide, malondialdehyde, and heat shock protein-70, and intestinal mRNA levels for interleukin-1β, interferon-γ, and chemokine (C-X-C motif) ligand-9; and the numbers of Enterobacterium family, Enterococcus genus and Clostridium coccoides in the colon digesta. Furthermore, AAB supplementation enhanced (P < 0.05): the plasma concentrations of serine, aspartate, glutamate, cysteine, tyrosine, phenylalanine, tryptophan, lysine, arginine, citrulline, ornithine, taurine, and γ-aminobutyric acid; intestinal villus height and surface area, villus height/crypt depth ratio, antioxidative enzyme activities, and mRNA levels for porcine β-defensin-1, sodium-independent amino acid transporters (b^0,+AT and y⁺LAT1), aquaporin (AQP) 3, AQP8, AQP10, nuclear factor erythroid 2-related factor 2 and glutathione S-transferase omega-2, and protein abundances of AQP3, AQP4, claudin-1, occludin and myxovirus resistance 1; and the numbers of Bifidobacterium genus and Lactobacillus genus in the colon digesta. Collectively, these comprehensive results indicate that dietary AAB supplementation plays an important role in improving piglet growth and intestinal function.

Mucosal Immunity and Protective Efficacy of Intranasal Inactivated Influenza Vaccine Is Improved by Chitosan Nanoparticle Delivery in Pigs

Annually, swine influenza A virus (SwIAV) causes severe economic loss to swine industry. Currently used inactivated SwIAV vaccines administered by intramuscular injection provide homologous protection, but limited heterologous protection against constantly evolving field viruses, attributable to the induction of inadequate levels of mucosal IgA and cellular immune responses in the respiratory tract. A novel vaccine delivery platform using mucoadhesive chitosan nanoparticles (CNPs) administered through intranasal (IN) route has the potential to elicit strong mucosal and systemic immune responses in pigs. In this study, we evaluated the immune responses and cross-protective efficacy of IN chitosan encapsulated inactivated SwIAV vaccine in pigs. Killed SwIAV H1N2 (δ-lineage) antigens (KAg) were encapsulated in chitosan polymer-based nanoparticles (CNPs-KAg). The candidate vaccine was administered twice IN as mist to nursery pigs. Vaccinates and controls were then challenged with a zoonotic and virulent heterologous SwIAV H1N1 (γ-lineage). Pigs vaccinated with CNPs-KAg exhibited an enhanced IgG serum antibody and mucosal secretory IgA antibody responses in nasal swabs, bronchoalveolar lavage (BAL) fluids, and lung lysates that were reactive against homologous (H1N2), heterologous (H1N1), and heterosubtypic (H3N2) influenza A virus strains. Prior to challenge, an increased frequency of cytotoxic T lymphocytes, antigen-specific lymphocyte proliferation, and recall IFN-γ secretion by restimulated peripheral blood mononuclear cells in CNPs-KAg compared to control KAg vaccinates were observed. In CNPs-KAg vaccinated pigs challenged with heterologous virus reduced severity of macroscopic and microscopic influenza-associated pulmonary lesions were observed. Importantly, the infectious SwIAV titers in nasal swabs [days post-challenge (DPC) 4] and BAL fluid (DPC 6) were significantly (p < 0.05) reduced in CNPs-KAg vaccinates but not in KAg vaccinates when compared to the unvaccinated challenge controls. As well, an increased frequency of T helper memory cells and increased levels of recall IFNγ secretion by tracheobronchial lymph nodes cells were observed. In summary, chitosan SwIAV nanovaccine delivered by IN route elicited strong cross-reactive mucosal IgA and cellular immune responses in the respiratory tract that resulted in a reduced nasal viral shedding and lung virus titers in pigs. Thus, chitosan-based influenza nanovaccine may be an ideal candidate vaccine for use in pigs, and pig is a useful animal model for preclinical testing of particulate IN human influenza vaccines.

Dietary Supplementation with Oleum Cinnamomi Improves Intestinal Functions in Piglets

The present study was to determine the efficacy of dietary supplementation with oleum cinnamomi (OCM) on growth performance and intestinal functions in piglets. Sixteen piglets (24-day-old) were randomly assigned to the control or OCM groups. Piglets in the control group were fed a basal diet, whereas piglets in the OCM group were fed the basal diet supplemented with 50 mg/kg OCM. On day 20 of the trial, blood samples and intestinal tissues were obtained from piglets. Compared with the control group, dietary OCM supplementation increased (p < 0.05) average daily feed intake, plasma insulin levels, villus width and villous surface area in the duodenum and jejunum, DNA levels and RNA/DNA ratios in the ileum, the abundance of Enterococcus genus and Lactobacillus genus in caecum digesta, mRNA levels for epithelial growth factor receptor (EGFR), Ras, extracellular signal-regulated kinase 1/2 (Erk1/2), b-cell lymphoma-extra large (Bcl-xL), villin, junctional adhesion molecule A (JAM-A), myxovirus resistance (MX) 1, MX2 and regenerating islet-derived protein 3 gamma (REG3G), and protein abundances of Ras and claudin-1, but decreased (p < 0.05) diarrhoea incidence; the abundances of Enterobacteriaceae family, Enterococcus genus, Lactobacillus genus, Bifidobacterium genus, and Clostrium coccoides in the colon digesta, and AMP-activated protein kinase (AMPK) mRNA levels and caspase-3 protein abundance in the jejunal mucosa of piglets. Taken together, these data indicate that dietary OCM supplementation modulates intestinal microbiota and improves intestinal function in weanling pigs. OCM is an effective feed additive and alternative to feed antibiotics for improving intestinal health in swine.

N-Acetylcysteine improves intestinal function in lipopolysaccharides-challenged piglets through multiple signaling pathways

This study determined whether N-acetylcysteine (NAC) could improve intestinal function through phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), epithelial growth factor receptor (EGFR), toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB), adenosine 5'-monophosphate-activated protein kinase (AMPK), and type I interferon (IFN) signaling pathways in a piglet model of lipopolysaccharides (LPS) challenge. Thirty-two piglets (24-day-old) were randomly allocated to one of four treatments, with eight replicates per treatment and one piglet per replicate. The experiment consisted of four treatments in a 2 × 2 factorial arrangement with two diets (supplemented with 0 or 500 mg NAC/kg diet) and saline or LPS administration. On day 20 of the trial, piglets in the LPS and LPS + NAC groups were intraperitoneally injected with 0 (saline) or 100 μg LPS/kg BW. Blood samples were obtained at 3 h and intestinal mucosae were collected at 6 h post LPS or saline injection. The growth performance was not affected by dietary NAC. LPS induced intestinal dysfunction, as indicated by: (1) reductions in the small-intestinal glutathione concentrations and plasma D-xylose levels; (2) elevations in plasma diamine oxidase activity, mucosal MMP3 mRNA levels and caspase-3 protein abundance; (3) reduced the activities of the small-intestinal mucosal maltase, sucrase and lactase. The adverse effects of LPS on porcine intestinal function and redox status were mitigated by NAC supplementation through the activation of multiple signaling pathways involving PI3K/Akt/mTOR, EGFR, TLR4/NF-κB, AMPK, and type I IFN. Our findings provide novel mechanisms for beneficial effects of NAC in protecting the intestine from inflammation in animals.

Assessment of the effect of grape seed cake inclusion in the diet of healthy fattening-finishing pigs

Modulatory capacity of bioactive compounds from different wastes has been scarcely investigated in pigs. This study aimed to evaluate the effects of dietary inclusion of grape seed cakes (GS diet) on performance and plasma biochemistry parameters as health indicators, as well as on several markers related to inflammation and antioxidant defence in the liver of fattening-finishing pigs. Twelve cross-bred pigs (TOPIG) were randomly assigned to one of two experimental diets: control and 5% grape seed cake diet during finishing period (24 days). No effect of GS diet on pig performance and blood biochemistry was observed. However, GS diet decreased significantly (-9.05%, p < .05) the cholesterol concentration (85.71 ± 0.94 mg/dl vs 94.24 ± 2.16 mg/dl) and increased IgA level (+49.90%, p < .05) in plasma (5.04 ± 0.5 mg/ml vs 3.36 ± 0.7 mg/ml). GS cakes decreased the inflammatory response in the liver of pigs fed with GS diet by lowering the Gene expression and protein concentration of pro-inflammatory cytokines (IL-1β, IL-8, TNF-α and IFN-γ) as well as the mRNA abundances of NF-κB signalling molecules. The antioxidant status was not increased by GS diet. The gene expression and activity of catalase decreased significantly. The gene expression of Nrf2, superoxide dismutase, glutathione peroxidase and heat-shock protein decreased, and no effect on their activity was observed with the exception of catalase activity which decreased. However, TBARS was reduced significantly. GS diet showed a modulatory effect on antioxidative status as well as anti-inflammatory and hypocholesterolic properties without effect on pig performance.

Salmonella in Swine: Microbiota Interactions

For the important foodborne pathogen Salmonella enterica to cause disease or persist in pigs, it has evolved an intricate set of interactions between itself, the host, and the indigenous microflora of the host. S. enterica must evade the host's immune system and must also overcome colonization resistance mediated by the pig's indigenous microflora. The inflammatory response against S. enterica provides the bacteria with unique metabolites and is thus exploited by S. enterica for competitive advantage. During infection, changes in the composition of the indigenous microflora occur that have been associated with a breakdown in colonization resistance. Healthy pigs that are low-level shedders of S. enterica also exhibit alterations in their indigenous microflora similar to those in ill animals. Here we review the literature on the interactions that occur between swine, S. enterica, and the indigenous microflora and discuss methods to reduce or prevent colonization of pigs with S. enterica.

Feeding of Enterococcus faecium NCIMB 10415 Leads to Intestinal miRNA-423-5p-Induced Regulation of Immune-Relevant Genes

Probiotics are widely used in human and animal health, but little is known about the mode of action of probiotics. One possible mechanism at the molecular level could be an influence on microRNAs (miRNAs) and the related immune-relevant target genes. Here, we analyzed differential expression of miRNA and potential target genes of ileal and jejunal lymphatic tissues from Enterococcus faeciumNCIMB 10415-fed piglets versus untreated controls by using next-generation sequencing. We identified miR-423-5p as being greatly affected by the treatment group (2.32-fold;P= 0.014). Validation by reverse transcription-quantitative PCR (RT-qPCR) confirmed a significant upregulation of miR-423-5p (2.11-fold;P= 0.03) and, additionally, downregulation of the important immune-relevant immunoglobulin lambda light C region (IGLC) (0.61-fold;P= 0.03) and immunoglobulin kappa constant (IGKC) (0.69-fold;P= 0.04) target genes. Expression analysis of miR-423-5p and IGLC at different age points shows a clear anti correlated relationship. Luciferase reporter assays with a HeLa cell line verified IGLC as a target of miR-423-5p. The results provided evidence for an effect of feeding of E. faeciumon the expression of miR-423-5p and on the regulation of the IGLC gene through miR-423-5p. This might be a possible mode of action of E. faeciumon immune cell regulation in the small intestine.

Transcriptional analysis of porcine intestinal mucosa infected with Salmonella Typhimurium revealed a massive inflammatory response and disruption of bile acid absorption in ileum

Infected pork meat is an important source of non-typhoidal human salmonellosis. Understanding of molecular mechanisms involved in disease pathogenesis is important for the development of therapeutic and preventive strategies. Thus, hereby we study the transcriptional profiles along the porcine intestine during infection with Salmonella Typhimurium, as well as post-transcriptional gene modulation by microRNAs (miRNA). Sixteen piglets were orally challenged with S. Typhimurium. Samples from jejunum, ileum and colon, collected 1, 2 and 6 days post infection (dpi) were hybridized to mRNA and miRNA expression microarrays and analyzed. Jejunum showed a reduced transcriptional response indicating mild inflammation only at 2 dpi. In ileum inflammatory genes were overexpressed (e.g., IL-1B, IL-6, IL-8, IL1RAP, TNFα), indicating a strong immune response at all times of infection. Infection also down-regulated genes of the FXR pathway (e.g., NR1H4, FABP6, APOA1, SLC10A2), indicating disruption of the bile acid absorption in ileum. This result was confirmed by decreased high-density lipoprotein cholesterol in serum of infected pigs. Ileal inflammatory gene expression changes peaked at 2 dpi and tended to resolve at 6 dpi. Furthermore, miRNA analysis of ileum at 2 dpi revealed 62 miRNAs potentially regulating target genes involved in this inflammatory process (e.g., miR-374 and miR-451). In colon, genes involved in epithelial adherence, proliferation and cellular reorganization were down-regulated at 2 and 6 dpi. In summary, here we show the transcriptional changes occurring at the intestine at different time points of the infection, which are mainly related to inflammation and disruption of the bile acid metabolism.

Overview and potential unifying themes of the atypical chemokine receptor family

Chemokines modulate immune responses through their ability to orchestrate the migration of target cells. Chemokines directly induce cell migration through a distinct set of 7 transmembrane domain G protein-coupled receptors but are also recognized by a small subfamily of atypical chemokine receptors, characterized by their inability to support chemotactic activity. Atypical chemokine receptors are now emerging as crucial regulatory components of chemokine networks in a wide range of physiologic and pathologic contexts. Although a new nomenclature has been approved recently to reflect their functional distinction from their conventional counterparts, a systematic view of this subfamily is still missing. This review discusses their biochemical and immunologic properties to identify potential unifying themes in this emerging family.

Quantitative proteomics and bioinformatic analysis provide new insight into the dynamic response of porcine intestine to Salmonella Typhimurium

The enteropathogen Salmonella Typhimurium (S. Typhimurium) is the most commonly non-typhoideal serotype isolated in pig worldwide. Currently, one of the main sources of human infection is by consumption of pork meat. Therefore, prevention and control of salmonellosis in pigs is crucial for minimizing risks to public health. The aim of the present study was to use isobaric tags for relative and absolute quantification (iTRAQ) to explore differences in the response to Salmonella in two segment of the porcine gut (ileum and colon) along a time course of 1, 2, and 6 days post infection (dpi) with S. Typhimurium. A total of 298 proteins were identified in the infected ileum samples of which, 112 displayed significant expression differences due to Salmonella infection. In colon, 184 proteins were detected in the infected samples of which 46 resulted differentially expressed with respect to the controls. The higher number of changes in protein expression was quantified in ileum at 2 dpi. Further biological interpretation of proteomics data using bioinformatics tools demonstrated that the expression changes in colon were found in proteins involved in cell death and survival, tissue morphology or molecular transport at the early stages and tissue regeneration at 6 dpi. In ileum, however, changes in protein expression were mainly related to immunological and infection diseases, inflammatory response or connective tissue disorders at 1 and 2 dpi. iTRAQ has proved to be a proteomic robust approach allowing us to identify ileum as the earliest response focus upon S. Typhimurium in the porcine gut. In addition, new functions involved in the response to bacteria such as eIF2 signaling, free radical scavengers or antimicrobial peptides (AMP) expression have been identified. Finally, the impairment at of the enterohepatic circulation of bile acids and lipid metabolism by means the under regulation of FABP6 protein and FXR/RXR and LXR/RXR signaling pathway in ileum has been established for the first time in pigs. Taken together, our results provide a better understanding of the porcine response to Salmonella infection and the molecular mechanisms underlying Salmonella-host interactions.