Quantitation of porcine cytokine and beta 2-microglobulin mRNA expression by reverse transcription polymerase chain reaction

Dynamics of cytokine gene expression in peripheral blood mononuclear cells of indigenous and exotic breeds of pigs in India

To incorporate immune competence traits in swine breeding programs, association between immune responsiveness and susceptibility to specific infectious diseases must be established. In order to understand the differences in immune competence between indigenous (Zovawk) and exotic (Large White Yorkshire: LWY) pigs reared in India, we carried out a time course expression analysis of immune-regulating key cytokine genes (interleukin (IL)-2, interferon (IFN)-γ, IL-4 and IL-10) in the phytohemagglutinin-P stimulated peripheral blood mononuclear cells (PBMCs). The IL-2 transcript levels in PBMCs increased several thousand-fold when compared to unstimulated cells in both the breeds, albeit the response in that of Zovawk was remarkably higher. Higher and earlier IFN-γ and IL-4 expression levels in Zovawk pigs suggest that both T_H 1 and T_H 2 immune responsiveness of this indigenous breed affords better preparedness for danger signals. Moreover, the low expression levels of IL-10 depict a regulated adaptive immune responsiveness. Remarkable difference between the two breeds of the pigs is evident showing a clear advantage of the Zovawk over LWY in terms of a shorter lag period of adaptive immune response. These findings provide a lead for understanding the genetic differences with respect to immune competence levels of indigenous pigs compared to exotic counterparts.

An in vitro alveolar macrophage assay for the assessment of inflammatory cytokine expression induced by atmospheric particulate matter

Exposures to air pollution in the form of particulate matter (PM) can result in excess production of reactive oxygen species (ROS) in the respiratory system, potentially causing both localized cellular injury and triggering a systemic inflammatory response. PM-induced inflammation in the lung is modulated in large part by alveolar macrophages and their biochemical signaling, including production of inflammatory cytokines, the primary mechanism via which inflammation is initiated and sustained. We developed a robust, relevant, and flexible method employing a rat alveolar macrophage cell line (NR8383) which can be applied to routine samples of PM from air quality monitoring sites to gain insight into the drivers of PM toxicity that lead to oxidative stress and inflammation. Method performance was characterized using extracts of ambient and vehicular engine exhaust PM samples. Our results indicate that the reproducibility and the sensitivity of the method are satisfactory and comparisons between PM samples can be made with good precision. The average relative percent difference for all genes detected during 10 different exposures was 17.1%. Our analysis demonstrated that 71% of genes had an average signal to noise ratio (SNR) ≥ 3. Our time course study suggests that 4 h may be an optimal in vitro exposure time for observing short-term effects of PM and capturing the initial steps of inflammatory signaling. The 4 h exposure resulted in the detection of 57 genes (out of 84 total), of which 86% had altered expression. Similarities and conserved gene signaling regulation among the PM samples were demonstrated through hierarchical clustering and other analyses. Overlying the core congruent patterns were differentially regulated genes that resulted in distinct sample-specific gene expression "fingerprints." Consistent upregulation of Il1f5 and downregulation of Ccr7 was observed across all samples, while TNFα was upregulated in half of the samples and downregulated in the other half. Overall, this PM-induced cytokine expression assay could be effectively integrated into health studies and air quality monitoring programs to better understand relationships between specific PM components, oxidative stress activity and inflammatory signaling potential.

Heat stress upregulation of Toll-like receptors 2/4 and acute inflammatory cytokines in peripheral blood mononuclear cell (PBMC) of Bama miniature pigs: an in vivo and in vitro study

Global warming is a challenge to animal health, because of increased heat stress, with subsequent induction of immunosuppression and increased susceptibility to disease. Toll-like receptors (TLR) are pattern recognition receptors that act as sentinels of pathogen invasion and tissue damage. Ligation of TLRs results in a signaling cascade and production of inflammatory cytokines, which eradicate pathogens and maintain the health of the host. We hypothesized that the TLR signaling pathway plays a role in immunosuppression in heat-stressed pigs. We explored the changes in the expression of TLR2, TLR4 and the concentration of acute inflammatory cytokines, such as IL-2, IL-8, IL-12 and IFN-γ in Bama miniature pigs subjected to 21 consecutive days of heat stress, both in vitro and in vivo models. The results showed that heat stress induced the upregulation of cortisol in the plasma of pigs (P<0.05); TLR4 mRNA was elevated, but IL-2 was reduced in peripheral blood mononuclear cells (PBMC, P<0.05). The white blood cell count and the percentage of granulocytes (eosinophilic+basophilic) decreased significantly in heat-stressed pigs (P<0.05). In the in vitro model (PBMC heat shocked for 1 h followed by a 9 h recovery period), TLR2 and TLR4 mRNA expression also increased, as did the concentration of IL-12 in supernatants. However, IFN-γ was significantly reduced in PBMC culture supernatants (P<0.05). We concluded that a consecutive heat stress period elevated the expression of TLR2 and TLR4 in PBMC and increased the plasma levels of inflammatory cytokines. These data indicate that TLR activation and dysregulation of cytokine expression in response to prolonged heat stress may be associated with immunosuppression and increased susceptibility to antigenic challenge in Bama miniature pigs.

Evaluation of suitable reference genes for gene expression studies in porcine PBMCs in response to LPS and LTA

Background

As an in vitro model porcine peripheral blood mononuclear cells (PBMCs) is frequently used as for immunogenetic research with the stimulation of bacterial antigens. To investigate the immunocompetence of PBMCs for recognition of Gram-positive and Gram-negative bacteria and in order to dissect the pathogenesis of diseases, gene expression assay is most commonly used. The gene expressions are required to normalize for reference genes which have tremendous effect on the results of expression study. The reference genes should be stably expressed between different cells under a variety of experimental conditions, but recent influx of data showed that expression stability of reference genes are varied under different experimental conditions. But data regarding the expression stability of reference genes in porcine PBMCs are limited. Therefore, this study was aimed to know whether the expression stability of commonly used reference genes in PBMCs is affected by various bacterial antigens under different experimental conditions in pigs.

Results

The mRNA expression stability of nine commonly used reference genes (B2M, BLM, GAPDH, HPRT1, PPIA, RPL4, SDHA, TBP and YWHAZ) was determined by RT-qPCR in PBMCs that were stimulated by LPS and LTA in vitro as well as cells un-stimulated control and non-cultured were also consider for this experiment. mRNA expression levels of all genes were found to be affected by the type of stimulation and duration of the stimulation (P < 0.05). geNorm software revealed that in case of irrespective of stimulation (without considering the type of stimulation), RPL4, PPIA and B2M were the most stable reference genes in PBMCs; in case of the control group, PPIA, BLM and GAPDH were the most stable reference genes. PPIA, B2M and RPL4 were the most stable reference genes in LPS stimulated PBMCs; and YWHAZ, RPL4 and PPIA were the most stably expressed reference genes in the case of LTA stimulated PBMCs. When LPS was used combined with LTA for the stimulation, YWHAZ, B2M and SDHA remained the most stable genes. PPIA, BLM and GAPDH were found to be most stably expressed reference genes when PBMCs were not cultured. NormFinder revealed different sets of stably expressed reference genes in PBMCs under different experimental conditions. Moreover, geNorm software suggested that the geometric mean of the three most stable genes would be the suitable combination for accurate normalization of gene expression study.

Conclusion

There was discrepancy in the ranking order of reference genes obtained by different analysing algorithms (geNorm and NormFinder). In conclusion, the geometric mean of the RPL4, B2M and PPIA seemed to be the most appropriate combination of reference genes for accurate normalization of gene expression data in porcine PBMCs without knowing the type of bacterial pathogenic status of the animals and in the case of mixed infection with Gram-negative and Gram-positive bacteria. In case of PBMCs without any stimulation, PPIA, BLM and GAPDH could be suggested as suitable reference genes.

The interaction between PRRSV and the late gestation pig fetus

Porcine reproductive and respiratory syndrome virus (PRRSV) crosses the placenta during late gestation and productively infects the fetus. Virus replication and cytokine responses were measured in tissues of fetuses recovered at 109–112 days of gestation, just prior to parturition. At the time of recovery, gross anatomical abnormalities were evident in both infected and non-infected fetuses from the infected dams. Virus isolation and immunohistochemistry identified the thymus as the primary site of virus replication. Steady state RT-PCR amplification of inflammatory, Th1 and Th2 cytokines, showed elevated IFN-γ and TNF-α mRNAs in tissues from infected fetuses, which corresponded to elevated cytokine proteins in serum but not amniotic fluid. Further evidence for induction of immunity was found in the hyperplastic response of lymph nodes, which included the development of germinal centers occupied CDw75+ B cells. Collectively, these data support the notion that the immunocompetent fetus is capable of initiating an antiviral response, which is compartmentalized within the infected fetus. Furthermore, fetal pathology may not be a direct result of virus replication in the fetus.

Effects of antigen and recombinant porcine cytokines on pig dendritic cell cytokine expression in vitro

To evaluate variables influencing in vitro immune response induction, pig monocyte-derived DCs (moDCs) were treated with putative type-1 and type-2 antigens (Ags, killed Mycobacterium tuberculosis (Mtb) and hen egg white lysozyme (HEWL)) and recombinant porcine cytokines (IL-6, IL-10, IL-12, IFN-gamma and TNF-alpha). Responses were measured as moDC cytokine mRNA expression. Treatment of moDCs with HEWL increased IL-13 but not IL-12, IFN-gamma or IL-10 mRNA, suggesting a DC2 phenotype. Addition of TNF-alpha, IFN-gamma or IL-12 to HEWL-treated moDCs increased IL-12p35 and reduced IL-13 mRNA; suggesting a DC1 phenotype. Mtb increased moDC IL-12p35, IFN-gamma and to a lesser extent IL-13 mRNA. This DC1 bias was enhanced by TNF-alpha, IFN-gamma or IL-12, which increased IL-12p35 and to a lesser extent IL-10 mRNA but reduced IL-13 mRNA. Addition of IL-10 to Mtb-pulsed moDCs reduced IL-12p35, IFN-gamma and IL-13, but increased IL-10 mRNA, suggesting diversion from DC1 to DC2. Thus porcine moDCs treated with Ag and/or cytokines alter moDC cytokine expression confirming their likely ability to initiate and steer acquired immune response.

Toll-like receptor, MHC II, B7 and cytokine expression by porcine monocytes and monocyte-derived dendritic cells in response to microbial pathogen-associated molecular patterns

To evaluate effects of treatment with pathogen-associated molecular patterns (PAMPs) on toll-like receptor (TLR), MHC II, B7 and cytokine expression, pig monocytes and monocyte-derived DCs (moDCs) were treated with LPS, CpG, lipoteichoic acid (LTA), poly IC or peptidoglycan (Pep). Monocytes and moDCs treated with LPS, CpG, LTA, poly IC or Pep altered expression of at least one TLR (4, 5 and 9) and up-regulated MHC II and/or B7. The mRNA for IL-4 was not detected after any treatment. Treatment with LPS or LTA tended to up-regulate mRNA for TLR 4, Th-1 (IFN-gamma and IL-12p35) and Th-2 cytokines (IL-10 and IL-13). Poly IC or CpG tended to up-regulate TLR 9 and Th-1 cytokines. Porcine monocytes and moDCs like those of humans and mice responded to microbial PAMPs by altering TLR expression, up-regulating MHC II and B7 and altering cytokine expression toward Th-1 and/or Th-2, which may steer immune response. Hence, porcine moDCs and monocytes are likely able to discriminate between microorganisms using TLRs which determine cytokine expression and immune response bias.

A quantitative real-time PCR method for tissue factor mRNA

BACKGROUND

Tissue factor (TF) is primarily known for its function to initiate blood coagulation. The range of in vivo expression of TF is wide and requires a dynamic assay for monitoring. A general method for TF mRNA quantitation that is dynamic, sensitive and applicable to a variety of experimental systems or clinical situations is therefore desirable.

OBJECTIVES

To develop a method for sensitive and dynamic quantitation of TF mRNA in human blood cells.

METHODS

TF mRNA expression was analysed and evaluated in monocyte isolations, in whole blood (healthy volunteers and patients scheduled for percutaneous coronary intervention, PCI) and in a panel of human cell lines. RNA was extracted, reverse transcribed and subjected to real-time PCR amplification, according to the TaqMan technology. A TF plasmid was constructed as calibrator of the assay. Two housekeeping genes used as endogenous controls for cDNA quality and integrity were evaluated.

RESULTS

The assay was linear by seven orders of magnitude and detected down to 10(2) copies of the TF plasmid. The coefficient of variation was 4% intra-assay and 28% between the assays when using beta2MG as endogenous control. The beta-actin gene expression was induced by treatment with lipopolysaccharide (LPS) in blood leukocytes and could not be used as an endogenous control. However, beta2MG showed only minor variations upon treatment with LPS. The TF mRNA and antigen expression, measured in a Western blot, correlated well (R(2)=0.903) in a panel of 11 human cell lines.

CONCLUSIONS

We have established a method for sensitive and dynamic quantitation of TF mRNA in experimental systems and for clinical situations.

Th-1/Th-2 type cytokine profiles of pig T-cells cultured with antigen-treated monocyte-derived dendritic cells

To examine the effects of cytokine environment at the time of antigenic exposure on T-cell cytokine profiles following T-cell-antigen presenting cell (APC) interaction, pig monocyte-derived dendritic cells (mDCs) were treated with hen egg white lysozyme (HEWL) or killed Mycobacterium tuberculosis (Mtb) alone or with a recombinant pig cytokine (TNF-alpha, interleukin (IL)-12, IL-10, interferon (IFN)-gamma or IL-6) and then incubated with autologous T-cell-enriched lymphocytes. Messenger RNA was isolated from the T-cells and used to evaluate the effects of treatment on IL-12p35, IFN-gamma, IL-4, IL-10 and IL-13 expression using RT-PCR. T-cells exposed to HEWL-treated mDCs expressed high IL-13 and moderate IL-10 and IFN-gamma, suggesting T-helper 2 (Th-2) bias. Addition of any cytokine during HEWL treatment of mDCs reduced subsequent expression of IL-10 and IL-13 by T-cells. Added IL-12 increased IFN-gamma mRNA. T-cells exposed to Mtb-treated mDCs expressed increased IFN-gamma and decreased IL-10 suggesting Th-1 bias. Addition of cytokines to mDCs treated with Mtb altered T-cell cytokine mRNA expression such that TNF-alpha, IFN-gamma or IL-12 increased IFN-gamma; IL-12 and IFN-gamma suppressed IL-10, while IL-10 and IL-12 enhanced IL-13. Messenger RNA for IL-4 and IL-12p35 was not detected in the T-cells. Results suggest Th-1/Th-2 type response bias in pigs T-cells as a function of antigen type and that cytokine environment at the time of antigen-mDC interaction alters cytokine profiles of T-cells responding to antigen-pulsed mDCs. Hence, cytokines may allow designed steering of porcine immune response.

Assessment of subacute inflammatory and proliferative response to coronary stenting in a porcine model by local gene expression studies and histomorphometry

The aim of the study was to analyse inflammatory and proliferative response early after coronary stenting by angiography, histomorphometry and local gene expression analysis using quantitative rt-PCR. Therefore, eight German domestic pigs underwent stenting of the left coronary artery. Selective coronary angiography was performed after 14 days. Explanted coronary arteries were examined histomorphometrically after methacrylate-embedding. Snap-frozen samples were examined for local gene expression of TGF-beta, TNF-alpha, GM-CSF, VEGF, PDGF and Fas Ligand (FasL) by real-time quantitative rt-PCR normalized to the housekeeping gene GAPDH and compared to unstented coronary arteries. All stented coronaries were patent with only little neointima formation. The median vessel diameter was 2.55 mm (range 2.43-2.68 mm). Histopathology revealed little inflammatory response limited to the tissue surrounding the stent struts; luminal area ranged from 84% to 91%. Compared to unstented control arteries, no significant differences in local gene expression were detected for VEGF, PDGF, TGF-beta, TNF-alpha and GM-CSF. Expression of FasL was upregulated as little as 1.7-fold (p=0.01). We conclude that, in native coronary arteries, no significant upregulation of investigated genes regulating vascular remodelling, inflammation or fibrogenesis was demonstrated 14 days after stenting. Whether upregulation of FasL as a marker gene of apoptosis is transient and biological significant requires further investigation.

House keeping genes and gene expression analysis in transplant recipients: a note of caution

BACKGROUND

House keeping genes are often used as a means of standardising results obtained in gene expression investigations. This study was performed to investigate whether beta-actin, beta2-microglobulin (two genes frequently quoted as house keeping genes) and/or transferrin receptor would be suitable house keeping genes for use in gene expression analysis of renal transplant recipients.

METHODS

Sequential expression of all three genes was measured in the peripheral blood mononuclear cells of 13 living donors and 45 renal transplant recipients, pre-operatively and then daily for up to 2 weeks. Fifteen of the recipients experienced an episode of biopsy proven acute rejection. Gene expression measurement was performed using quantitative real time 'TaqMan' PCR technology.

RESULTS

Gene expression of all three genes was unchanged in the living donor cohort. However, in the transplant recipients there were significant increases in expression following transplantation in the non-rejectors, and preceding the diagnosis of acute rejection. In the latter group, levels returned to pre-transplant values after the commencement of anti-rejection therapy.

CONCLUSIONS

Beta-actin, beta2-microglobulin and transferrin receptor gene expression, although not influenced by surgery, is influenced by transplantation, acute rejection and anti-rejection therapy making these genes unsuitable as house keeping genes following renal transplantation. These findings may cast doubt on the results of some studies that used these genes for the purposes of standardisation when looking at cDNA measurement. We suggest that any group wishing to use a house keeping gene ensure that its expression is independent of study parameters prior to the start of the study.

Kinetic study of porcine GM-CSF expression in porcine alveolar macrophages and spleen cells

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important regulator in inducing differentiation and proliferation of immune cells. The functional roles of porcine GM-CSF (pGM-CSF) have not yet been revealed. Therefore, expression patterns of pGM-CSF were investigated in immune cells after cloning and sequencing of whole pGM-CSF cDNA. Whole cDNA of pGM-CSF was amplified from porcine alveolar macrophages stimulated by lipopolysaccharide (LPS), using 5'- and 3'-rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR) methods. The products of 5'- and 3'-RACE-PCR were cloned, and the nucleotide sequence of whole pGM-CSF cDNA was determined (GenBank accession number AY116504). The kinetics of pGM-CSF mRNA expression were studied in porcine immune cells such as alveolar macrophages and spleen cells, using a real-time quantitative PCR. The expression of pGM-CSF in LPS-, phytohemagglutinin (PHA)-, or concanavalin A (ConA)-stimulated cells was always higher as compared to the control cells. The expression levels of pGM-CSF in alveolar macrophages were highest at 5 h after LPS stimulation and then continuously decreased in the late phase. In spleen cells, the LPS-stimulated group showed the highest levels after 5 h, but the PHA- and the ConA-stimulated groups showed slightly increased expression levels at the early phase and peaked at 24 h. To our knowledge, this is the first published report describing the nucleotide sequence of whole cDNA and the expression pattern of pGM-CSF using real-time quantitative PCR. These results indicate that pGM-CSF has its own characteristic expression profile in different immune cells.

Control of immunoglobulin isotype production by porcine B-cells cultured with cytokines

Cytokines regulate immunoglobulin (Ig) isotype production following the Th1/Th2 paradigm, derived from studies of inbred mice. In pigs, it is not known which, if any, Ig isotypes may reflect a Th1/Th2 response. To evaluate this, purified porcine CD21(+) B-cells were co-cultured with Staphylococcus aureus Cowan strain 1 or Escherichia coli lipopolysaccharide as B-cell mitogens together with recombinant human IL-2, and recombinant porcine (rp) interferon (IFN)-gamma, IL-12 or IL-10. While the mitogens increased B-cell proliferation, cytokines had no additional effect. A quantitative competitive enzyme-immuno assay was used to measure concentrations of porcine IgM, IgG(1) and IgG(2) in B-cell culture supernatants. In vitro, porcine B-cells produced IgG(2), 106 +/- 17.3 microg/ml; IgG(1) 107 +/- 38.3 microg/ml and IgM 25.6 +/- 8.45 microg/ml. In some individuals, Th1 cytokines such as rpIFN-gamma and IL-12, enhanced IgG(2) in the face of low concentrations of IgG(1). Furthermore, individual responses, in some cases, tended to be diametrically opposed, reminiscent of previously documented categorical immune responses in pigs such that some individuals produced high concentrations of IgG(1) in response to the various doses of rp cytokines, while others produced lower concentrations. Pigs may generate a high IgG(1):IgG(2) ratio in response to rpIL-10, and possibly to other Th2-associated cytokines. However, B-cell response to rp cytokines in vitro exhibits marked variation by pig, a feature that is likely a function of highly variable individual genotypes and their interaction with complex environments.

Evaluation of cytokine gene expression in porcine spleen cells, peripheral blood mononuclear cells, and alveolar macrophages by competitive RT-PCR

Cytokines act as an important regulator of immune responses. Since cytokine expression levels are generally very low, more accurate and reliable methods of measuring their expression are needed. In this study, a modified competitive reverse transcription-polymerase chain reaction assay was developed to determine the expression levels and patterns of porcine IFN-gamma, IL-2, IL-4, IL-10, IL-12 p 35, and IL-12 p40 in spleen cells, peripheral blood mononuclear cells (PBMC), and alveolar macrophages that were stimulated for 4 h by lipopolysaccharide or phytohemagglutinin. Of these cytokines, the expression level of IFN-gamma was the highest in all examined cells. Constitutive expression of IL-2 and IL-4 was demonstrated in spleen cells and PBMC stimulated with phytohemagglutinin. However, their expression extent was not determinable or extremely low in the lipopolysaccharide-stimulated spleen cells and alveolar macrophages. Moderately high IL-10 expression was observed in all examined cells. IL-12 p 35 expression in alveolar macrophages was always higher than in spleen cells and PBMC. IL-12 p40 expression in alveolar macrophages was higher than in PBMC, but was lower than in spleen cells. In spleen cells, the expression of IL-12 p40 was higher than that of IL-12 p 35. In alveolar macrophages and PBMC, however, IL-12 p 35 showed a higher expression than IL-12 p40. These results indicate that each cytokine has its own characteristic expression profile in different immune cells.

T helper 1-type cytokine transcription in peripheral blood mononuclear cells of pseudorabies virus (Suid herpesvirus 1)-primed swine indicates efficient immunization

The induction of porcine cytokines, which are believed to be important for the regulation of T helper (Th)1- and Th2-specific immune responses of pigs, was analysed after in vitro restimulation with a herpesvirus, Suid herpes 1 (pseudorabies virus [PRV]), in peripheral blood mononuclear cells (PBMC). To this end, quantitative, competitive reverse transcription-polymerase chain reaction (RT-qcPCR) was established using constructed heterologous DNA MIMICS, which contain cytokine- or glyceraldehyde-3-phosphate dehydrogenase (GAPDH)-specific primer-binding sites. This is a simple method that allows reliable determination of the differing regulation of cytokine mRNAs specific for porcine interleukin (IL)-2, -4 and -10, interferon gamma (IFN-gamma) and the housekeeping gene, GAPDH, as an endogenous control. PBMC derived from naive (innate response) and PRV-primed (memory response) outbred swine were analysed comparatively. The results demonstrated that restimulation with PRV significantly enhanced the transcription of Th1-type cytokines (IL-2 and IFN-gamma) but not of Th2-type cytokines (IL-4 and IL-10). This virus-specific cytokine response was only found with PBMC from swine protected against lethal PRV challenge infection, but not with naive PBMC or with PBMC from pigs immunized with plasmid DNA encoding PRV glycoprotein gC. Notably, PBMC derived from immune and naive pigs constitutively produced relatively high amounts of IL-10-specific mRNA, exceeding that of GAPDH mRNA, independently of the addition of viral antigen or the mitogen concanavalin A (Con A). The results of this work should help to provide a better understanding of the effector cell/cytokine network response to infection with, or vaccination against, PRV. Additionally, the simple, reliable and sensitive RT-qcPCR, when used to determine the porcine cytokine pattern, might be of prognostic value for the induction of protective immunity.

Cytokine mRNA expression in leukocytes of efferent lymph from stimulated lymph nodes in pigs

To test the hypothesis that characteristic cytokine responses occur in stimulated porcine lymph nodes (LNs), lymph node efferent ducts were surgically cannulated. Efferent lymph (EL) leukocytes were collected before and after stimulation of LNs with mitogens [bacterial lipopolysaccharide (LPS) or phytohemagglutinin-P(PHA-P)] and antigens [hen egg white lysozyme (HEWL) or purified protein derivative of tuberculin (PPD)]. Cytokine mRNA expression was evaluated by quantitative reverse transcription polymerase chain reaction (Q-RT-PCR). Interleukin (IL)-1alpha was predominantly produced after all stimuli except for HEWL after which tumour necrosis factor (TNF)-alpha message was dominant. None of the stimuli induced message for IL-2, IL-4 or IL-8. Other cytokine mRNAs were produced in variable amounts and percentage of overall production of each cytokine message was in the following descending rank: LPS: IL-1alpha, TNF-alpha, interferon (IFN)-gamma, IL-10, IL-12-p35, IL-6, IL-12-p40 and TNF-beta; PHA-P: IL-1alpha, TNF-alpha, IL-10, IFN-gamma, IL-12-p40 and TNF-beta; HEWL: TNF-alpha, IL-1alpha, IFN-gamma, IL-10, IL-6, IL-12-p40, TNF-beta and IL-12-p35 and PPD: IL-1alpha, IFN-gamma, TNF-alpha and IL-10. Time course response of cytokines revealed early (IL-1alpha, 10, TNF-alpha) and intermediate (IL-12-p40, TNF-beta, IFN-gamma) responses for PHA-P and early (IL-1alpha, 6, 10, IL-12-p35, IL-12-p40, TNF-alpha), intermediate (TNF-beta, IFN-gamma) and late (IL-1alpha, 6) for LPS. Cytokine mRNA response induced by HEWL was early (IL-alpha, IFN-gamma), intermediate (IL-10, IL-12-p40, TNF-beta), late (IL-1alpha, IL-12-p35) and very late (IL-1alpha, 6, 10, IL-12-p40, TNF-alpha). In Bacillus Calmette-Guérin (BCG) sensitized pigs, stimulation of LNs with PPD induced message for IL-1alpha, 10, TNF-alpha and IFN-gamma which peaked at 24h. Cytokine mRNAs varied by stimulus and differed for antibody and cell-mediated immune response.

Cytokines in Mycoplasma hyorhinis-induced arthritis in pigs bred selectively for high and low immune responses

Yorkshire pigs were bred selectively for high and low immune responses (H and L pigs, respectively) based on multiple antibody (Ab) and cell-mediated immune response traits. In a previous experiment, generation 4 (G4) pigs of each line were infected with Mycoplasma hyorhinis. High responders had a more rapid and higher Ab response and less polyserositis, but arthritis was more severe in H pigs than in L pigs. To test the hypothesis that line differences were attributable to differential expression of cytokines, M. hyorhinis infection was induced in pigs of G8. Arthritis was more severe clinically (P, </=0.05) and postmortem (P, </=0.001) when M. hyorhinis CFU were more numerous in synovial fluid (SF) of H pigs than of L pigs (P, </=0.03). In H pigs but not L pigs, CFU and lesion scores were correlated positively. In H pigs, infection increased the frequency of expression of mRNAs for interleukin-8 (IL-8), IL-10, and tumor necrosis factor alpha (TNF-alpha) in mononuclear cells from synovial membranes (SM). In L pigs, IL-1alpha, IL-6, IL-10, and TNF-alpha mRNAs were increased in frequency of expression. The quantity of the cytokine message for IL-6 was increased in infected H pigs. For L pigs, infection increased the cytokine message for IL-1alpha, IL-6, IL-10, and TNF-alpha. IL-6 in SM and gamma interferon (IFN-gamma) in SF were produced at a higher copy number in H pigs than in L pigs after infection. For H pigs, there were no positive rank correlations between lesion or CFU scores and cytokines. For L pigs, IL-1alpha, IL-8, IL-10, and TNF-alpha in SM correlated with CFU, while IL-6, TNF-beta, and IFN-gamma in SF correlated with CFU. Lesion score in L pigs correlated with IL-1alpha in SF. While these results indicate that H and L pigs differ in the cytokine response to M. hyorhinis infection, they do not confirm a characteristic cytokine response in association with the relative susceptibility to infection and arthritis observed in H pigs.