Ontogeny and characterization of blood leukocyte subsets and serum proteins in piglets before and after weaning

Effects of Antrodia cinnamomea solid culture mycelium by-products on growth performance and immune response in weaning black piglets

This study evaluated the effects of supplementation with Antrodia cinnamomea mycelium by-product (ACBP) on growth performance and immune response in weaning piglets. Total available content and antioxidant capacity of ACBP were determined. Ninety-six black pigs were randomly distributed to 24 pens. Study compared four groups which were supplemented with ACBP at 0%, 2.5%, 5%, or 10% for 6 weeks after weaning at 4 weeks. Results showed that ACBP on total phenolic, total flavonoid, and total triterpenoids contents were 13.68 mg GAE/g DW, 1.67 μg QE/g DW, and 15.6 mg/g, respectively. Weaning piglets fed 2.5% ACBP showed a significant decreased body weight gain compared with those supplemented with 5% ACBP, 10% ACBP, and control groups. Results showed that all ACBP groups increased the villi height of jejunum significantly. Incidence of diarrhea in 11 weeks with supplementation with 5% and 10% ACBP diets were lower than in control group. The 10% ACBP group showed significantly lower expression of immune response genes (IL-1β, IL-6, IL-8, TNF-α, and IFN-γ) than the 2.5% and 5% ACBP groups. Based on results, dietary supplementation with 10% ACBP did not significantly affect body weight but could decrease piglet diarrhea condition and expression of IL-1β and IL-6 genes.

Effects of improved early-life conditions on health, welfare, and performance of pigs raised on a conventional farm

Nowadays, most pigs are raised indoors, on intensive farms providing a poor environment. In these conditions, the risk of the occurrence of damaging behaviours is high, with dramatic consequences for animal health and welfare as well as economic losses for farmers. Early-life conditions may predispose individuals to develop damaging behaviours later in life. In contrast, reinforcing affiliative behaviours between piglets before weaning might help to prevent tail-biting episodes. In this field study, we aimed at improving early-life conditions of piglets on a commercial farm by completely suppressing painful procedures and staggering their exposure to weaning stress factors. The alternative early-life management strategy combined housing in free-farrowing pens with temporary crating of the sow, socialisation during the lactation period with whole-life maintenance of the hierarchical groups, and delayed transfer to the postweaning room after sow removal. Control conditions included birth in farrowing crates, tail docking, absence of socialisation during the lactation period, abrupt weaning with immediate transfer to the postweaning room and mixing with non-littermates. We evaluated the health, welfare, and performance of alternatively raised pigs (n = 80) as compared to controls (n = 75). Visits were made throughout the lifespan of individuals to evaluate their growth and health status. Body and tail lesions were scored as proxy measures of aggressiveness and impaired welfare. Blood and bristle samples were periodically collected to evaluate stress, inflammation and immune competence. While the whole-life performance of pigs was similar among groups, the alternative early-life conditions prevented the growth slowdown usually observed after weaning. In addition, alternatively raised pigs displayed more neutrophils, eosinophils and monocytes the day after weaning, as well as higher C-Reactive Protein levels. One week later, their monocytes displayed greater phagocytic capacity. Altogether, these data suggest an enhanced innate immune competence for alternatively raised pigs around weaning. Piglets reared under alternative conditions also exhibited fewer and less severe body lesions than standard pigs, one week after weaning. In contrast, they showed more tail lesions on days 36 and 66 associated with greater levels of acute phase proteins (C-Reactive Protein and haptoglobin). To conclude, alternative early-life management better prepared piglets for weaning. However, the whole-life maintenance of early-established social groups was not sufficient to prevent the occurrence of damaging behaviours in undocked pigs.

Pathogen exposure influences immune parameters around weaning in pigs reared in commercial farms

BACKGROUND

Multiple antigenic stimulations are crucial to immune system training during early post-natal life. These stimulations can be either due to commensals, which accounts for the acquisition and maintenance of tolerance, or to pathogens, which triggers immunity. In pig, only few works previously explored the influence of natural exposition to pathogens upon immune competence. We propose herein the results of a multicentric, field study, conducted on 265 piglets exposed to contrasted pathogen levels in their living environment. Piglets were housed in 15 different commercial farms, sorted in two groups, low (HS^LOW)- and high (HS^HIGH)-health status farms, depending on their recurrent exposition to five common swine pathogens.

RESULTS

Using animal-based measures, we compared the immune competence and growth performances of HS^LOW and HS^HIGH pigs around weaning. As expected, we observed a rise in the number of circulating leucocytes with age, which affected different cell populations. Monocyte, antigen-experienced and cytotoxic lymphocyte subpopulation counts were higher in piglets reared in HS^LOW farms as compared to their HS^HIGH homologs. Also, the age-dependent evolution in γδ T cell and neutrophil counts was significantly affected by the health status. With age, circulating IFNα level decreased and IgM level increased while being greater in HS^LOW piglets at any time. After weaning, LPS-stimulated blood cells derived from HS^LOW piglets were more prone to secrete IL-8 than those derived from HS^HIGH pigs did. Monocytes and granulocytes issued from HS^LOW pigs also exhibited comparable phagocytosis capacity. Altogether our data emphasize the more robust immunophenotype of HS^LOW piglets. Finally, piglets raised under higher pathogen pressure grew less than HS^HIGH piglets did and exhibited a different metabolic profile. The higher cost of the immune responses associated with the low farm health status may account for lower HS^LOW piglet performances.

CONCLUSIONS

Altogether, our data, obtained in field conditions, provide evidence that early exposure to pathogens shapes the immune competence of piglets. They also document the negative impact of an overstimulation of the immune system on piglets' growth.

Different local, innate and adaptive immune responses are induced by two commercial Mycoplasma hyopneumoniae bacterins and an adjuvant alone

Introduction

Enzootic pneumonia still causes major economic losses to the intensive pig production. Vaccination against its primary pathogen, Mycoplasma hyopneumoniae, is carried out worldwide to control the disease and minimize clinical signs and performance losses. Nonetheless, the effects of both infection with, and vaccination against Mycoplasma hyopneumoniae on the innate and adaptive immune responses remain largely unknown. Therefore, we conducted a study in which piglets were injected once with a commercial bacterin V1 or V2, or the adjuvant of V1 (A) to investigate their effect on local, innate and adaptive immune responses.

Methods

Three weeks after vaccination, piglets were challenge infected with M. hyopneumoniae and euthanized four weeks later to assess vaccine efficacy via macroscopic and microscopic evaluation of lung lesions. Blood and broncho-alveolar lavage fluid (BAL) samples were collected to measure antibody responses, cellular immunity, BAL cytokine levels and BAL M. hyopneumoniae DNA load as well as cytokine secretion by monocytes.

Results

After vaccination, proliferation of antigen-specific CD3⁺ T cells and a higher percentage of TNF-α⁺ CD8⁺, and TNF-α⁺ and TNF-α⁺IFN-γ⁺ CD4⁺CD8⁺ T cells was seen in V1, while proliferation of or a significant increase in cytokine production by different T cell subsets could not be observed for animals from V2. Interestingly, LPS-stimulated blood monocytes from V1 and A secreted less IL-10 on D7. After challenge, higher levels of IgA, more IL-10 and less IL-1β was detected in BAL from V1, which was not observed in V2. Animals from A had significantly more IL-17A in BAL. The macroscopic lung lesion score and the M. hyopneumoniae DNA load at euthanasia was lower in V1, but the microscopic lung lesion score was lower in both vaccinated groups.

Discussion

In conclusion, these results indicate that the two commercial bacterins induced different local and adaptive immune responses, that the adjuvant alone can reduce anti-inflammatory innate immune responses, and that both vaccines had a different efficacy to reduce Mycoplasma-like lung lesions and M. hyopneumoniae DNA load in the lung.

Intrinsic challenges of neonatal adaptation in swine

Abstract. The losses of piglets in commercial pig farming remain at concerning levels and need to be addressed through the implementation of new sustainable breeding and management strategies. In fact, piglets are especially at risk in the first days of life. Both genetics and the farrowing process have been shown to impact piglet vitality. In addition, knowledge of the animal-intrinsic responses in adapting to extra-uterine life is particularly important but is scarcely described in the scientific literature. In this review, the three phases that constitute neonatal adaptation in the pig are systematically presented. The first phase of early adaptation involves primarily the development of cardiorespiratory function (within the first 10 min of life) as well as thermoregulatory processes and acid–base balance (up to 24 h of life). In the second phase, homeostasis is established, and organ maturation takes place (up to 14 d post natum). The final third phase aims at the development of neurological, immunological and muscular features (up to 28 d of life). The involvement of aggravating and ameliorating factors such as dystocia, low colostrum yield and heat supply is key to the development of strategies to reduce piglet losses and increase vitality. The insights are of particular value in addressing current concerns in pig farming and to further improve animal welfare in pig production across different management types.

Effect of Porcine Colostral Exosomes on T Cells in the Peripheral Blood of Suckling Piglets

Simple Summary

Exosomes in porcine colostrum have gained attention as the possible key compounds involved in the growth and/or development of suckling piglets. In this study, peripheral blood mononuclear cells (PBMCs) from suckling piglets were cultured with or without milk-derived exosomes (control) in vitro. Porcine colostral exosomes increased the proportion of cytotoxic T (Tc) cells, while this phenomenon was not observed in PBMC whose endocytosis was inhibited. Moreover, exosome-treated PBMCs had a higher cytokine IL-2 concentration in the culture supernatant than the control. The present study demonstrated that porcine colostral exosomes could increase the Tc cell proportion in the peripheral blood of a suckling piglet, with the underlying mechanism believed to be the stimulation of IL-2 production in PBMCs via endocytosis.

Abstract

Growing evidence indicates that porcine colostral exosomes may contribute to the healthy development of piglets. Here, we evaluated in vitro the effect of porcine milk-derived exosomes, in particular colostral exosomes, on T cells in the peripheral blood of suckling piglets. A total of seven sows and thirteen suckling piglets were used. Peripheral blood mononuclear cells (PBMCs) from suckling piglets were cultured with or without milk-derived exosomes (control). Using flow cytometry, the proportion of each T cell subset in cultured PBMCs was analyzed three days post-incubation. PBMCs cultured with porcine colostral exosomes had a higher proportion of CD3⁺CD4⁻CD8⁺ T cells (cytotoxic T cells; Tc) than the control. However, exosomes induced no increase in the Tc cell population in PBMC whose endocytosis was inhibited. We further measured the concentrations of cytokines in the culture supernatant. Exosome-treated PBMCs had a higher cytokine IL-2 concentration than the control. The present study demonstrated that porcine colostral exosomes could increase the Tc cell proportion in the peripheral blood of suckling piglets, with the underlying mechanism believed to be the stimulation of IL-2 production in PBMCs via endocytosis. Moreover, our results suggested that porcine colostral exosomes were involved in the development of cellular immunity in suckling piglets.

Immunocyte Populations Observed from Birth to Weaning in Blood, Spleen and Mesenteric Lymph Nodes of Piglets

Susceptibility to pathogen infections and efficacy of vaccination highly depend on the immune status of the piglet. Here, we measured immunocytes in piglets from birth to weaning to elucidate how immunocyte populations change during development and are affected by weaning. Crossbred piglets were used. Suckling piglets were euthanized at 1, 7, 14, 21, 28 or 35 days old (3~4 piglets at each time point). In addition, seven piglets were weaned at 21 days old, with four being euthanized at 28 days old and the remaining at 35 days old. Piglet carcasses were dissected, and blood, mesenteric lymph nodes (MLN) and spleen were sampled. In total, seven antibodies were used to stain the immunocyte population. Dynamics of myeloid (CD3−SWC3+CD16+), natural killer (NK; CD3−SWC3−CD16+), killer T (CD3+CD8+), helper T (CD3+CD4+) and B (CD3−CD21+) cells were analyzed. Percentage of innate immunity cells such as myeloid cells declined (p < 0.05) from the first day after birth. In contrast, percentage of NK cells increased in piglets while they were still suckling. Killer T, helper T, and B cell populations increased around 2~3 weeks after birth. No significant differences in the populations of the evaluated cell types were observed between suckling and weaned piglets at least for 14 days post weaning.

Local and Systemic T Cell Immunity in Fighting Pig Viral and Bacterial Infections

T cells are an essential component of the adaptive immune system. Over the last 15 years, a constantly growing toolbox with which to study T cell biology in pigs has allowed detailed investigations on these cells in various viral and bacterial infections. This review provides an overview on porcine CD4, CD8, and γδ T cells and the current knowledge on the differentiation of these cells following antigen encounter. Where available, the responses of these cells to viral infections like porcine reproductive and respiratory syndrome virus, classical swine fever virus, swine influenza A virus, and African swine fever virus are outlined. In addition, knowledge on the porcine T cell response to bacterial infections like Actinobacillus pleuropneumoniae and Salmonella Typhimurium is reviewed. For CD4 T cells, the response to the outlined infections is reflected toward the Th1/Th2/Th17/Tfh/Treg paradigm for functional differentiation. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 10 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

An engineered anti-idiotypic antibody-derived killer peptide (KP) early activates swine inflammatory monocytes, CD3+CD16+ natural killer T cells and CD4+CD8α+ double positive CD8β+ cytotoxic T lymphocytes associated with TNF-α and IFN-γ secretion

This study evaluated the early modulation of the phenotype and cytokine secretion in swine immune cells treated with an engineered killer peptide (KP) based on an anti-idiotypic antibody functionally mimicking a yeast killer toxin. The influence of KP on specific immunity was investigated using porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) as ex vivo antigens. Peripheral blood mononuclear cells (PBMC) from healthy pigs were stimulated with KP and with a scramble peptide for 20 min, 1, 4 and 20 h or kept unstimulated. The cells were analyzed using flow cytometry and ELISA. The same time-periods were used for KP pre-incubation/co-incubation to determine the effect on virus-recalled interferon-gamma (IFN-γ) secreting cell (SC) frequencies and single cell IFN-γ productivity using ELISPOT. KP induced an early dose-dependent shift to pro-inflammatory CD172α⁺CD14^+high monocytes and an increase of CD3⁺CD16⁺ natural killer (NK) T cells. KP triggered CD8α and CD8β expression on classical CD4^-CD8αβ⁺ cytotoxic T lymphocytes (CTL) and double positive (DP) CD4⁺CD8α⁺ Th memory cells (CD4⁺CD8α^+low CD8β^+low). A fraction of DP cells also expressed high levels of CD8α. The two identified DP CD4⁺CD8α^+high CD8β^+low/+high CTL subsets were associated with tumor necrosis factor alpha (TNF-α) and IFN-γ secretion. KP markedly boosted the reactivity and cross-reactivity of PRRSV type-1- and PCV2b-specific IFN-γ SC. The results indicate the efficacy of KP in stimulating Th1-biased immunomodulation and support studies of KP as an immunomodulator or vaccine adjuvant.

Impact of birth weight and neonatal nutritional interventions with micronutrients and bovine colostrum on the development of piglet immune response during the peri-weaning period

Immune system development of piglets is influenced by birth weight and colostrum and milk intake. Moreover, the dam transfer to piglets of vitamins A and D and copper, which play important role in immunity, is limited during lactation. In this study, we evaluated the potential of maternal and neonatal supplementations with vitamins A and D and copper, with or without neonatal supplementation of bovine colostrum (BC), to modulate the immune system development of low birth weight (LBW) and high birth weight (HBW) piglets during the peri-weaning period. Litters from 23 control sows (CONT) were assigned to one of the following treatments: 1) control (C); 2) oral administration at 2 and 8 days (d) of age of retinol-acetate, 25-hydroxyvitamin D and CuSO₄ and exposure to UVB light for 15 min every second day from d 5 to d 21 (ADCu); 3) oral administration of dehydrated BC (4 g/d) from d 5 to d 10 (BC); 4) ADCu + BC. This experimental design was repeated with 24 sows fed extra daily supplements of 25-hydroxyvitamin D (4,000 IU), β-carotene (30,000 IU) and Cu-yeast (equivalent 45 mg of Cu) from 90 d of gestation until weaning at d 21 (SUPPL). Within each litter, 2 LBW and 2 HBW piglets were euthanized at d 16 and d 23 in order to characterize leukocyte subsets in mesenteric lymph nodes (MLN) and blood by flow cytometry, and to measure gene expression in the MLN and jejunal mucosa by qPCR. At d 16, results revealed that the percentages of γδ and cytotoxic T lymphocytes were significantly reduced in LBW compared to HBW piglets. The jejunal expression of interleukin (IL) 22 was also up-regulated, along with MLN expression of C-C Motif Chemokine Ligand 23, bone morphogenetic protein 2 and secreted phosphoprotein 1 (SPP1), whereas jejunal expression of tumor necrosis factor α was decreased in LBW piglets. At d 23, LBW piglets showed lower amounts of γδ T lymphocytes, higher percentages of CD3^- and CD3^-CD8α⁺CD16⁺ leukocytes (which include Natural killer cells) and lower jejunal expression of IL18. Furthermore, supplementation with BC increased the blood percentage of CD3^-CD16⁺ leukocytes and reduced jejunal IL5 and MLN IL15 expression whereas supplementation with ADCu + BC increased jejunal TNF superfamily 13B and MLN SPP1 expression. Our results suggest that immune system development after birth differed between LBW and HBW piglets and that early dietary supplementation with BC and ADCu has the potential to modulate development of immune functions.

The porcine tonsils and Peyer's patches: A stereological morphometric analysis in conventionally and artificially reared piglets

Selection for prolificacy in modern pig farming has resulted in increasing litter sizes. Since rearing large litters is challenging, artificial rearing of piglets with a milk replacer is an alternative strategy. It is hypothesized that the development of the piglets' mucosa-associated lymphoid tissues (MALT) is affected by these artificial conditions. Therefore, the stereologically estimated volumes of the tonsil of the soft palate, and the lingual, nasopharyngeal and paraepiglottic tonsils, as well as the jejunal and ileal Peyer's patches were statistically compared at day 21 postpartum between six conventionally reared piglets and six piglets that were artificially reared from day 7 onwards. In addition, six 7-day-old sow-fed piglets were examined to evaluate the effect of age. All tonsils and Peyer's patches significantly increased in volume with age. The rearing strategy had no significant effect on the volumes of the tonsil of the soft palate and the lingual tonsil. The former tonsil was by far the largest with a mean volume of 967.2 ± 122.4 mm³ and 822.3 ± 125.4 mm³ in the conventionally and artificially reared piglets, respectively. The lingual tonsil only measured 9.4 ± 6.4 mm³ and 6.3 ± 2.6 mm³ in conventionally and artificially reared groups, respectively. In contrast, the rearing strategy did affect the volumes of the nasopharyngeal and paraepiglottic tonsils, which had a mean volume of 137.1 ± 32.4 mm³ and 84.4 ± 26.9 mm³, and 30.7 ± 7.8 mm³ and 20.0 ± 3.9 mm³ in conventionally and artificially reared piglets, respectively. The rearing strategy did not affect the development of the Peyer's patches. At day 21, the jejunal Peyer's patches of the conventionally and artificially reared piglets presented a volume of 1.6 ± 0.4 cm³ and 1.3 ± 0.2 cm³, respectively. The volumes of the ileal Peyer's patch amounted to 15.1 ± 3.0 cm³ in conventionally reared piglets and 12.0 ± 2.6 cm³ in artificially reared piglets at day 21. The results showed that artificial rearing hampers the morphological development of the tonsils that are exposed to inhaled antigens, but the voluminous lymphoid tissues that sample oral antigens are not influenced. Since it is unlikely that the observed differences in both tonsils are due to the milk replacer, artificial rearing could be a valuable alternative for raising large litters. In addition, the presence of developing MALT in piglets allows for investigating the value of nasal and oral vaccination in this species for human or veterinary purposes.

Piglet weight gain during the first two weeks of lactation influences the immune system development

The aim of this study was to investigate the effect of the piglet growth during the first week of life on ileal expression of genes and on development of the immune system. Eight litters adjusted to 12 piglets were used. Within each litter, the piglet that showed the lowest weight gain (LWG; n = 8) and the one that showed the highest weight gain (HWG; n = 8) in their first week of life were enrolled. Peripheral blood mononuclear cells (PBMC) were isolated on days 8 and 16 to characterize cellular population profiles and to assess ex-vivo secretion of interleukin-10 (IL-10), IL-6 and tumor necrosis factor-α (TNF-α). On day 16, piglets were euthanized and ileum samples were collected to extract RNA for microarray analysis and gene expression by qPCR. As expected, growth performance of LWG piglet was impaired compared to HWG piglets (P < 0.05). From day 8 to 16, the percentage of CD21⁺ B cells significantly increased in blood of heavier HWG piglets while the percentage remained constant in smaller LWG piglets (P weight x day = 0.01). For the CD4⁺CD8α^- Th cells, a marked increase was observed in LWG piglets from 8 to 16 days of age (P =  0.002) whereas no significant change occurred in HWG piglets. Percentages of CD14⁺ monocytes and other MHC-II⁺ cells were respectively higher and lower on day 8 compared to day 16 for both groups of piglets (P <  0.01). On day 8, LPS-activated PBMC from LWG piglets produced less IL-6 compared to HWG piglets (P <  0.05). Microarray analysis of gene expression in piglets' ileum tissue indicated that several genes involed in defense response and response to oxidative stress were modulated differently in LWG compared to HWG. Gene analysis by Q-PCR confirmed microarray results and revealed that IL-10, SOD1, NOS2, NOD2, TLR4, TLR9, CD40 and CD74 expressions were significantly decreased (P < 0.05) in LWG in comparison to HWG piglets, while MYD88 and NFkBiA showed a tendency to decrease (0.05 ≤ P < 0.07). These results suggest that birth weight and milk intake affect the growth performances and the development of immunity by modulating the expression of genes associated with immunity and oxidative stress in piglets' intestinal tissue, and by affecting the leukocyte populations involved in innate and cell-mediated immunity in nursing piglets. Therefore, impaired development of immune system in LWG piglets might have an impact on their resistance to infections later in life.

Gene expression profiles of CD4/CD8 double-positive T cells in porcine peripheral blood

A characteristic subset of T cells, known as double positive T cells (DPTC) and expressing both cluster of differentiation 4 (CD4) and CD8, is observed in porcine peripheral blood. Previous studies suggested that DPTC might be memory cells. However, detailed phenotypes and functions of DPTC are yet to be fully elucidated and thus, the relatedness of DPTC with memory phenotypes remains unclear. In this study, DPTC gene expression profiles in peripheral blood were analyzed by DNA microarray in Experiment 1 and compared with those of CD4 single positive T cells (4SPTC) and CD8 single positive T cells (8SPTC). Expressions of IFNG, CCL5, NCK2, CCR2 and ITGB1 were higher than that of 4SPTC and 8SPTC. In contrast, expressions of CCR7 and SELL were lower than that of 4SPTC and 8SPTC. These results suggested that DPTC were either effector T cells or effector memory T cells (T_EM ). Next, to determine whether DPTC were effector T cells or T_EM , differences in the response of DPTC and 8SPTC against immunized/primed antigens were compared (Experiment 2). While DPTC showed quick elevation of IL2 and CD25 gene expressions against in vitro stimulation of primed/immunized antigens, 8SPTC did not. These results suggest that at least some DPTC likely belong to T_EM .

Oral antibiotics increase blood neutrophil maturation and reduce bacteremia and necrotizing enterocolitis in the immediate postnatal period of preterm pigs

Immature immunity may predispose preterm neonates to infections and necrotizing enterocolitis (NEC). Intravenous antibiotics are frequently given to prevent and treat sepsis, while oral antibiotics are seldom used. We hypothesized that oral antibiotics promote maturation of systemic immunity and delay gut bacterial colonization and thereby protect preterm neonates against both NEC and bacteremia in the immediate postnatal period. Preterm pigs were given formula and administered saline (CON) or broad-spectrum antibiotics orally (ORA) or systemically (SYS) for 5 d after birth. Temporal changes in blood parameters and bacterial composition in the intestine, blood and immune organs were analyzed. Newborn preterm pigs had few blood neutrophils and a high frequency of progenitor cells. Neutrophils gradually matured after preterm birth with increasing CD14 and decreasing CD172a expressions. Preterm neutrophil and monocyte TLR2 expression and TLR2-mediated blood cytokine responses were low relative to adults. ORA pigs showed enhanced blood neutrophil maturation with reduced cell size and CD172a expression. Only ORA pigs, but not SYS pigs, were protected from a high density of gut Gram-positive bacteria, high gut permeability, Gram-positive bacteremia and NEC. Neonatal oral antibiotics may benefit mucosal and systemic immunity via delayed gut colonization and enhanced blood neutrophil maturation just after preterm birth.

Short-term pharmacokinetic study of mycophenolate mofetil in neonatal swine

BACKGROUND

Mycophenolate mofetil (MMF) is an effective immunosuppressive agent that has been frequently used in laboratory animals including swine; however, the pharmacokinetic properties of MMF in swine have not been studied. This short-term study was designed to evaluate the feasibility and the pharmacokinetic profiles of MMF therapy in neonatal swine.

MATERIALS AND METHODS

Twelve neonatal pigs were randomized into four groups including one control and three treated groups with oral MMF administered at 0.5, 1, and 2 g/m(2)/d for 4 days, divided by 2 half-doses at 9:00 and 17:00 (except day 4 during which MMF was not administered at 17:00). Blood samples were collected at 9:00 on days 0, 2, 3 and 4 for complete blood count and hepatic/renal function examination; the trough concentration of plasma mycophenolic acid (MPA) was also determined. On days 2 and 4, blood was collected to determine the area under the curve (AUC) of plasma MPA concentration. Animal body-weight growth and manifestations of MMF side-effects such as anorexia, vomiting, and diarrhea were also observed.

RESULTS

MMF has no acute hepatic/renal toxicity in newborn pigs; however, less body-weight growth was observed in treated groups. In the control group, a spontaneous increase of lymphocyte count was observed; in contrast, MMF therapy with doses of 1 and 2 g/m(2)/d reduced both lymphocyte and monocyte counts of piglets. Oral MMF had high bioavailability in neonatal swine. MPA-AUC0-12h of doses 0.5, 1, and 2 g/m(2)/d was 22.00 ± 3.32, 57.57 ± 34.30, and 140.00 ± 19.70 μg × h/mL, respectively. Neither MPA trough concentration (MPA-C0), nor MPA maximum concentration (MPA-Cmax) or MPA-AUC0-6h had high correlation with MMF-dose. For surveillance of MPA exposure, MPA-C0 had significant correlation with MPA-AUC0-12h (Spearman's ρ = 0.933, AUC0-12h = 17.882 × C0 + 14.479, r(2) = 0.966).

CONCLUSION

To reach adequate drug exposure and to reduce dose-dependent side effects, an MMF dose of 1 g/m(2)/d is recommended to be used as an initial dose for immunosuppressive therapy in piglets, and MPA-C0 monitoring is the most practical strategy for experimental transplantation study.

Selection based on indirect genetic effects for growth, environmental enrichment and coping style affect the immune status of pigs

Pigs living in intensive husbandry systems may experience both acute and chronic stress through standard management procedures and limitations in their physical and social environment, which may have implications for their immune status. Here, the effect of a new breeding method where pigs were selected on their heritable influence on their pen mates' growth, and environmental enrichment on the immune status of pigs was investigated. Hereto, 240 pigs with a relatively positive genetic effect on the growth of their pen mates (+SBV) and 240 pigs with a relatively negative genetic effect on the growth of their pen mates (-SBV) were housed in barren or straw-enriched pens from 4 to 23 weeks of age (n  =  80 pens in total). A blood sample was taken from the pigs before, three days after a 24 h regrouping test, and at week 22. In addition, effects of coping style, as assessed in a backtest, and gender were also investigated. Mainly, +SBV were found to have lower leukocyte, lymphocyte and haptoglobin concentrations than -SBV pigs. Enriched housed pigs had a lower neutrophil to lymphocyte (N:L) ratio and lower haptoglobin concentrations, but had higher antibody titers specific for Keyhole Limpet Hemocyanin (KLH) than barren housed pigs. No interactions were found between SBV class and housing. Furthermore, pigs with a proactive coping style had higher alternative complement activity and, in the enriched pens, higher antibody titers specific for KLH than pigs with a reactive coping style. Lastly, females tended to have lower leukocyte, but higher haptoglobin concentrations than castrated males. Overall, these results suggest that +SBV pigs and enriched housed pigs were less affected by stress than -SBV and barren housed pigs, respectively. Moreover, immune activation might be differently organized in individuals with different coping styles and to a lesser extent in individuals of opposite genders.

Zinc oxide influences intestinal integrity, the expressions of genes associated with inflammation and TLR4-myeloid differentiation factor 88 signaling pathways in weanling pigs

This study explored whether zinc oxide (ZnO) supplementation could alleviate weanling-induced intestinal injury through TLR and NOD-like receptor signaling pathways. Twelve early-weanling piglets were allotted to two dietary treatments (control vs 2200 mg Zn/kg from ZnO) for 1 wk. The results showed that supplemental ZnO improved daily gain and feed intake, decreased post weaning scour scores, increased villus height and villus height:crypt depth ratio at the jejunal mucosa, and decreased diamine oxidase activity and endotoxin concentration in plasma. The intestinal mRNA levels of TLR4 and its downstream signals, including MyD88, IL-1 receptor-associated kinase 1 and TNF-α receptor-associated factor 6, were decreased, and the expressions of intestinal pro-inflammatory cytokines and chemokines were decreased simultaneously in the ZnO-supplemented piglets. Although NF-κB p65 mRNA abundance was not affected by ZnO supplementation, NF-κB p65 protein expression was down-regulated by ZnO. However, ZnO supplementation had no effect on intestinal expressions of NOD1 and NOD2, and their adaptor molecule receptor-interacting serine/threonine-protein kinase 2, as well as protein expressions of caspase-3 and heat shock protein 70. The results indicated that the protective effects of ZnO on intestinal integrity were closely related to decreasing the expressions of genes associated with inflammation through inhibiting the TLR4-MyD88 signaling pathways.

Antibody responses to Sarcoptes scabiei apolipoprotein in a porcine model: relevance to immunodiagnosis of recent infection

No commercial immunodiagnostic tests for human scabies are currently available, and existing animal tests are not sufficiently sensitive. The recombinant Sarcoptes scabiei apolipoprotein antigen Sar s 14.3 is a promising immunodiagnostic, eliciting high levels of IgE and IgG in infected people. Limited data are available regarding the temporal development of antibodies to Sar s 14.3, an issue of relevance in terms of immunodiagnosis. We utilised a porcine model to prospectively compare specific antibody responses to a primary infestation by ELISA, to Sar s 14.3 and to S. scabiei whole mite antigen extract (WMA). Differences in the antibody profile between antigens were apparent, with Sar s 14.3 responses detected earlier, and declining significantly after peak infestation compared to WMA. Both antigens resulted in >90% diagnostic sensitivity from weeks 8-16 post infestation. These data provide important information on the temporal development of humoral immune responses in scabies and further supports the development of recombinant antigen based immunodiagnostic tests for recent scabies infestations.

Phenotypic maturation of porcine NK- and T-cell subsets

Detailed information concerning the development of the immune system in young pigs is still rudimental. In the present study, we analyzed changes in phenotype and absolute numbers of natural killer cells, γδ T cells, T helper cells, regulatory T cells and cytolytic T cells in the blood of pigs from birth to six months of age. For each lymphocyte subpopulation, a combination of lineage and differentiation markers was investigated by six-color flow cytometry. Major findings were: (i) absolute numbers of γδ T cells strongly increased from birth until 19-25 weeks of age, indicating an important role for these cells during adolescence; (ii) phenotype of T helper cells changed over time from CD8α(-)SLA-DR(-)CD27(+) towards CD8α(+)SLA-DR(+)CD27(-) but CD45RC(-) T helper cells were found immediately after birth, therefore questioning the role of this marker for the identification of T-helper memory cells; (iii) for cytolytic T cells, putative phenotypes for early effector (CD3(+)CD8αβ(+)perforin(+)CD27(dim)) and late effector or memory cells (CD3(+)CD8αβ(+)perforin(+)CD27(-)) could be identified.

Immunological characterization of peripheral blood leukocytes using vaccine for mycoplasmal pneumonia of swine (MPS) in swine line selected for resistance to MPS

This study was conducted to evaluate immunological changes in peripheral blood leukocytes in pigs that were genetically selected for their improved resistance to mycoplasmal pneumonia of swine (MPS), using MPS vaccine as an antigen. Twelve castrated MPS-selected Landrace pigs were compared with the same number of pigs from a nonselected line by using a time-course analysis at the hematological level. After the second sensitization with MPS vaccine, the percentages of B cells, CD4(+) T cells, and natural killer (NK) cells in total leukocytes were lower in the selected line than in the nonselected line, whereas the percentage of granulocytes in total leukocytes increased in the MPS-selected line. We also assessed the proliferative ability of peripheral blood mononuclear cells (PBMCs) stimulated with Mycoplasma hyopneumoniae, lipopolysaccharide or concanavalin A, and found that although the proliferative ability of the PBMC was not different between the two lines at a steady state, the nonselected line showed a significantly higher proliferative ability after sensitization with MPS vaccine than the selected line regardless of antigens used. These results thus indicate that the selection of pigs on the basis of MPS resistance changes their immunophenotype, and would give us beneficial information for the prevention of MPS infection.

The effect of an immunomodulator (parapoxvirus ovis) on cell-mediated immunity (CMI) in abruptly weaned foals

The weaning process of foals involves a period of considerable stress which likely contributes to an increased risk of infectious disease in these young horses. Mechanisms responsible for this heightened risk of infection remain unknown, although likely due to compromised cell-mediated immunity. Parapoxvirus ovis (PPVO), an immmunomodulator, has been shown to limit the severity of infectious disease outbreaks among horses and has been shown to enhance CMI responses. Thus, an objective of this study was to investigate the effect of PPVO therapy on cell-mediated immune (CMI) responses of abruptly weaned foals. A group of foals (n=6) were given an intramuscular injection of PPVO on days -2, 0 (weaning) and 9. An additional group of foals (n=5) received the diluent only on the same days serving as controls. Peripheral blood samples were collected from all foals prior to weaning (day 0) and on days 1, 3, 5, 7, 9, 11, 14, and 21 after weaning. Whole blood samples were prepared to determine in vivo cytokine mRNA expression by reverse transcription and real-time PCR (RT-PCR). Peripheral blood mononuclear cells (PBMC) were isolated and stimulated to determine in vitro cytokine production by intracellular staining using flow cytometry and gene expression was measured by RT-PCR. Cytokines analyzed in this study were interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) and interleukin-10 (IL-10). Regardless of PPVO treatment, foals undergoing the weaning process showed a significant decrease in both in vivo and in vitro cytokine (IFN-γ, TNF-α and IL-10) production. These results indicate that abrupt weaning significantly impacts CMI of the foal which may increase susceptibility to infectious agents.

MBL1 genotypes in wild boar populations from Sweden, Austria, the Czech Republic, and Japan

The single nucleotide polymorphism (SNP) G949T in the mannose-binding lectin ( MBL ) 1 gene has been associated with low MBL-A concentration in serum and detected at different frequencies in various European pig populations. However, the origin of this SNP is not known. Part of the MBL1 gene was sequenced in 12 wild boar/Large White crossbred pigs from the second backcross (BC 2 ) generation in a family material originating from two wild boar x Large White intercrosses. Also, MBL-A serum concentration was measured in the entire BC 2 generation (n = 45). Furthermore, the genotypes of 68 wild boars from Sweden, Austria, the Czech Republic, and Japan were determined in regard to five previously described SNPs in MBL1 . The T allele of G949T was present among the BC 2 animals. MBL-A serum concentration in the BC 2 animals showed a bimodal distribution, with one-third of the animals at levels between 0.7 and 1.6 μg mL(-1) and the remaining pigs at levels around 13 μg mL(-1) . There was a co-variation between the presence of the T allele and low MBL-A concentration in serum. The genotyping of the wild boars revealed differences between populations. The T allele of G949T was not detected in the Austrian and Japanese samples and is thus unlikely to be an original feature of wild boars. In contrast, it was present at high frequency (0.35) among the Swedish wild boars, probably representing a founder effect. Five MBL1 haplotypes were resolved. Only two of these were present among the Japanese wild boars compared to four in each of the European populations. This difference may reflect differences in selection pressure and population history.

Barley-derived β-glucans increases gut permeability, ex vivo epithelial cell binding to E. coli, and naive T-cell proportions in weanling pigs

Weaning in young animals is associated with an increased incidence of gastrointestinal infections. β-glucans exert numerous physiological effects, including altering immune function. The objective of this study was to determine the effects of feeding barley (Hordeum vulgare L.)-derived β-glucans on immune and intestinal function in weanling pigs (Sus scrofa). Thirty-one individually-housed Dutch Landrace pigs (21 d; initial BW, 6,298 ± 755 g) were weaned and fed a wheat-based diet (control) or a low (Lo-BG), medium (Med-BG), or high β-glucan-containing barley-based diet (Hi-BG) for 2 wk with 7 or 8 pigs/treatment. Intestinal segments were analyzed for permeability using Ussing chambers and K88 Escherichia coli adhesion to enterocytes was assessed ex vivo. Immune cells from mesenteric lymph nodes, peripheral blood, and Peyer's patches were analyzed for lymphocyte subsets by indirect immunofluorescence and the ability to respond ex vivo to mitogens by (3)H-thymidine incorporation. Hematology and neutrophil function were determined by flow cytometry. Neutrophil burst, size, and granularity, lymphocyte proliferation, and B-cell distribution in peripheral blood lymphocytes, Peyer's patches, and mesenteric lymph nodes were not affected by β-glucans content of the diet. The β-glucans content of the diet altered blood concentrations of erythrocytes and leukocytes, CD4, CD45RA, and CD8 blood cells (P < 0.05). In addition, feeding β-glucan resulted in increased (P < 0.05) percentage CD45RA positive cells in peripheral blood lymphocytes, Peyer's patches, and mesenteric lymph nodes. Mannitol permeability and tissue conductance were increased (P < 0.05) in Hi-BG fed pigs compared with control pigs. Percentage maximum K88-E.coli binding was increased in proportion to the β-glucan content of the diet (P < 0.05). Although β-glucan feeding during the weaning period increased blood lymphocytes and the proportion of naïve T-cells, it also increased E. coli-enterocyte binding and intestinal permeability. β-glucan may alter immune and intestinal function of weaning pigs.

The effect of dietary fatty acids on post-operative inflammatory response in a porcine model

The potential anti-inflammatory effects of dietary fish oil (FO) have been studied in numerous clinical trials. However, variation in lifestyle and morbidity among patients can be difficult to control. In the present study, the impact of a 3-week dietary pre-treatment with 10% (w/w) FO (n 28), sunflower oil (SO, n 28), or animal fat (AF, n 28) was evaluated with respect to post-operative responses in inflammatory markers in a porcine model on aortic vascular prosthetic graft infection. In the early post-operative period (0 < day ≤ 3), FO suppressed whole blood IL-8 and tumor necrosis factor-α responsiveness to LPS stimulation, decreased peripheral leukocyte IL-8 mRNA abundance, reinforced an increase in total leukocyte count, and counteracted a decrease in mononuclear leukocyte count compared with SO. In the late post-operative period (3 < day ≤ 14), FO increased total leukocyte count and showed higher maximum CRP and haptoglobin concentrations compared with SO. Compared with AF, FO decreased peripheral leukocyte IL-8 mRNA abundance in the early post-operative period, and increased total leukocyte count and maximum CRP concentration in the late post-operative period. In conclusion, the post-operative response in a number of inflammatory markers was affected by FO, and this was most apparent compared with SO.

Effects of different antimicrobial treatments on serum acute phase responses and leucocyte counts in pigs after a primary and a secondary challenge infection with Actinobacillus pleuropneumoniae

The susceptibility to an initial challenge and a re-challenge inoculation with Actinobacillus pleuropneumoniae was analysed in pigs that were treated with antimicrobials of different efficacies following the first exposure to A pleuropneumoniae. In brief, 30 nine-week-old specific pathogen-free pigs were allocated to five groups of six. After acclimatisation, four groups were inoculated with A pleuropneumoniae serotype 2. At the onset of clinical signs, three of the groups of pigs were treated with enrofloxacin, tetracycline or penicillin. A fourth group served as the inoculated control and the fifth group as a control group that had not been inoculated. On day 28, all five groups were re-challenged with the same strain of A pleuropneumoniae serotype 2 as had been used in the first inoculation. No treatments were carried out at this time. The acute phase responses and differential leucocyte counts were monitored in detail after both inoculations. Leucocytosis and acute phase responses in the forms of serum amyloid A, pig-major acute phase protein and haptoglobin were recorded in all of the inoculated groups after the onset of clinical signs following the first inoculation. A porcine mannan-binding lectin-A response was less evident in the pigs. Acute phase responses resembling those of the first inoculation were observed in the pigs that had not previously been inoculated and in the pigs treated with enrofloxacin. Acute phase responses were not recorded in the other three groups, where the pigs had seroconverted to A pleuropneumoniae serotype 2 following the first inoculation.

Glutamine supplementation improves intestinal barrier function in a weaned piglet model of Escherichia coli infection

The weaning period is associated with an increased prevalence of gastrointestinal infection in many species. Glutamine (Gln) has been shown to improve intestinal barrier function and immune function in both in vivo and in vitro models. The objective of the present study was to determine the effect of dietary Gln supplementation on intestinal barrier function and intestinal cytokines in a model of Escherichia coli infection. We randomised 21-d-old piglets (n 20) to nutritionally complete isonitrogenous diets with or without Gln (4·4 %, w/w) for 2 weeks. Intestinal loops were isolated from anaesthetised pigs and inoculated with either saline or one of the two E. coli (K88AC or K88 wild-type)-containing solutions. Intestinal tissue was studied for permeability, cytokine expression, fluid secretion and tight-junction protein expression. Animals receiving Gln supplementation had decreased potential difference (PD) and short-circuit current (I(sc)) in E. coli-inoculated intestinal loops (PD 0·628 (SEM 0·151) mV; I(sc) 13·0 (SEM 3·07) μA/cm(2)) compared with control-fed animals (PD 1·36 (SEM 0·227) mV; I(sc) 22·4 (SEM 2·24) μA/cm(2)). Intestinal tissue from control, but not from Gln-supplemented, animals responded to E. coli with a significant increase in mucosal cytokine mRNA (IL-1β, IL-6, transforming growth factor-β and IL-10). Tight-junction protein expression (claudin-1 and occludin) was reduced with exposure to E. coli in control-fed animals and was not influenced in Gln-supplemented piglets. Gln supplementation may be useful in reducing the severity of weaning-related gastrointestinal infections, by reducing the mucosal cytokine response and altering intestinal barrier function.

Severe gunshot injuries in a porcine model: impact on central markers of innate immunity

BACKGROUND

the mechanisms behind lipopolysaccharide (LPS) tolerance remain obscure. LPS signals through Toll-like receptor 4 (TLR4) and severe trauma/haemorrhage may influence binding and signalling through this receptor, e.g. by changing membrane expression or by releasing endogenous ligands like High Mobility Group Box 1 (HMGB1). The aim of this study was to examine these relations further in a porcine model with standardized trauma.

METHODS

nine anaesthetized pigs sustained one gunshot through the femur and one pistol shot through the upper abdomen. Blood was sampled before and 90 min after shooting. The samples were stimulated for 4 h with LPS 10 ng/ml or an equivalent amount of normal saline. The leucocyte response was evaluated by measuring the tumour necrosis factor-α (TNF-α) and CXC ligand 8 (CXCL8) in the supernatant. Flow cytometry was used to measure the surface expression of TLR4 on CD14+ monocytes. HMGB1 concentrations were measured in the plasma.

RESULTS

trauma and treatment caused a significant decline in the LPS-stimulated concentrations of TNF-α [4.53 ± 0.24 pg/ml (ln) at 0 min, 3.54 ± 0.35 pg/ml (ln) at 90 min, P=0.026], but did not modify the release of CXCL8. Monocyte TLR4 expression was unchanged. Plasma HMGB1 increased significantly [<0.92 vs. 3.02 ± 0.19 ng/ml (ln), P<0.001]. The concentrations of TNF-α and CXCL8 did not correlate with TLR4 expression or HMGB1 concentrations.

CONCLUSION

the results suggest that trauma-induced LPS tolerance is not primarily regulated by TLR4 expression on circulating CD14+ monocytes or by the release of HMGB1 from damaged tissues.

Ultra-early weaning in piglets results in low serum IgA concentration and IL17 mRNA expression

In pigs raised for meat production, weaning is a critical period because of related physiological perturbations and negative consequences on performance. Previous studies have shown that early weaning could either impair development of mucosal barrier function or boost intestinal immunologic parameters. In order to obtain further knowledge about the impact of ultra-early weaning on the porcine immune system development, three groups of piglets were weaned at different ages and compared to the unweaned control group. Lower IgA concentrations in ultra-early and early weaned piglets than in other piglets were identified in serum. In the mesenteric lymph node (MLN), significant differences in the mRNA expression of IL17a, TGF beta and FOXP3 were found between specific groups. Indeed, IL17a mRNA was mainly detected in ultra-early weaned piglets while FOXP3 and TGF beta mRNA were associated to both ultra-early weaned and suckling piglets. Reduced serum IgA concentration and MLN induction of a Th17 cytokine in ultra-early weaned piglets could be related to alterations of the mucosal barrier functions consecutive to the milk deprivation. All together, our findings suggest a crucial role for endogenous milk factors onto the onset of IgA synthesis.