Characterization of monoclonal antibodies to ovine tumor necrosis factor-alpha and development of a sensitive immunoassay

Effect of mesenchymal precursor cells on the systemic inflammatory response and endothelial dysfunction in an ovine model of collagen-induced arthritis

Background and Aim

Mesenchymal precursor cells (MPC) are reported to possess immunomodulatory properties that may prove beneficial in autoimmune and other inflammatory conditions. However, their mechanism of action is poorly understood. A collagen-induced arthritis model has been previously developed which demonstrates local joint inflammation and systemic inflammatory changes. These include not only increased levels of inflammatory markers, but also vascular endothelial cell dysfunction, characterised by reduced endothelium-dependent vasodilation. This study aimed to characterise the changes in systemic inflammatory markers and endothelial function following the intravenous administration of MPC, in the ovine model.

Methods

Arthritis was induced in sixteen adult sheep by administration of bovine type II collagen into the hock joint following initial sensitisation. After 24h, sheep were administered either 150 million allogeneic ovine MPCs intravenously, or saline only. Fibrinogen and serum amyloid-A were measured in plasma to assess systemic inflammation, along with pro-inflammatory and anti-inflammatory cytokines. Animals were necropsied two weeks following arthritis induction. Coronary and digital arterial segments were mounted in a Mulvaney-Halpern wire myograph. The relaxant response to endothelium-dependent and endothelium-independent vasodilators was used to assess endothelial dysfunction.

Results and Conclusion

Arthritic sheep treated with MPC demonstrated a marked spike in plasma IL-10, 24h following MPC administration. They also showed significantly reduced plasma levels of the inflammatory markers, fibrinogen and serum amyloid A, and increased HDL. Coronary arteries from RA sheep treated with MPCs demonstrated a significantly greater maximal relaxation to bradykinin when compared to untreated RA sheep (253.6 ± 17.1% of pre-contracted tone vs. 182.3 ± 27.3% in controls), and digital arteries also demonstrated greater endothelium-dependent vasodilation. This study demonstrated that MPCs given intravenously are able to attenuate systemic inflammatory changes associated with a monoarthritis, including the development of endothelial dysfunction.

Lymphotropism and host responses during acute wild-type canine distemper virus infections in a highly susceptible natural host

The mechanisms behind the in vivo virulence of immunosuppressive wild-type morbillivirus infections are still not fully understood. To investigate lymphotropism and host responses, we have selected the natural host model of canine distemper virus (CDV) infection in mink. This model displays multisystemic infection, similar to measles virus and rinderpest virus infections in their susceptible natural hosts. The wild-type CDVs investigated provoked marked virulence differences, inducing mild versus marked to severe acute disease. The mildly virulent wild-type virus induced transient lymphopenia, despite the development of massive infection of peripheral blood mononuclear cells (PBMCs) exceeding that determined for the highly virulent wild-type virus, indicating an inverse relationship between acute virulence and the extent of viraemia in the investigated wild-type viruses. Single-cell cytokine production in PBMCs was investigated throughout the acute infections. We observed Th1- and Th2-type cytokine responses beginning in the prodromal phase, and late inflammatory responses were shared between the wild-type infections.

Early biomarkers and potential mediators of ventilation-induced lung injury in very preterm lambs

Background

Bronchopulmonary dysplasia (BPD) is closely associated with ventilator-induced lung injury (VILI) in very preterm infants. The greatest risk of VILI may be in the immediate period after birth, when the lungs are surfactant deficient, still partially filled with liquid and not uniformly aerated. However, there have been very few studies that have examined this immediate post-birth period and identified the initial injury-related pathways that are activated. We aimed to determine if the early response genes; connective tissue growth factor (CTGF), cysteine rich-61 (CYR61) and early growth response 1 (EGR1), were rapidly induced by VILI in preterm lambs and whether ventilation with different tidal volumes caused different inflammatory cytokine and early response gene expression.

Methods

To identify early markers of VILI, preterm lambs (132 d gestational age; GA, term ~147 d) were resuscitated with an injurious ventilation strategy (V_T 20 mL/kg for 15 min) then gently ventilated (5 mL/kg) for 15, 30, 60 or 120 min (n = 4 in each). To determine if early response genes and inflammatory cytokines were differentially regulated by different ventilation strategies, separate groups of preterm lambs (125 d GA; n = 5 in each) were ventilated from birth with a V_T of 5 (VG5) or 10 mL/kg (VG10) for 135 minutes. Lung gene expression levels were compared to levels prior to ventilation in age-matched control fetuses.

Results

CTGF, CYR61 and EGR1 lung mRNA levels were increased ~25, 50 and 120-fold respectively (p < 0.05), within 30 minutes of injurious ventilation. VG5 and VG10 caused significant increases in CTGF, CYR61, EGR1, IL1-β, IL-6 and IL-8 mRNA levels compared to control levels. CTGF, CYR61, IL-6 and IL-8 expression levels were higher in VG10 than VG5 lambs; although only the IL-6 and CYR61 mRNA levels reached significance.

Conclusion

CTGF, CYR61 and EGR1 may be novel early markers of lung injury and mechanical ventilation from birth using relatively low tidal volumes may be less injurious than using higher tidal volumes.

Hypoxia Potentiates Endotoxin-Induced Allopregnanolone Concentrations in the Newborn Brain

BACKGROUND

Allopregnanolone is a neurosteroid produced in the brain that can alter the excitability of the CNS. Neurosteroids have neuroprotective properties, and their elevation in response to stress may protect the newborn brain following infection or hypoxia. Infection, particularly of the respiratory tract, may lead to episodes of hypoxia. Infection and hypoxia have been identified as factors contributing to neonatal morbidity and mortality.

OBJECTIVES

To determine the effect of acute episodes of hypoxia alone or in combination with lipopolysaccharide (LPS) exposure on plasma and brain allopregnanolone concentrations in lambs 10-21 days old. Also, to examine plasma levels of cortisol and the cytokines, tumour necrosis factor-alpha and interleutkin-6 after these challenges.

RESULTS

Allopregnanolone concentrations in the brain were markedly increased after hypoxia. Hypoxia following prior LPS treatment resulted in greater increases in brain allopregnanolone concentrations compared to either the LPS or hypoxia treatment alone. Importantly, brain regions unaffected by LPS or hypoxia alone (thalamus/hypothalamus, cerebellum) showed significant increases of allopregnanolone content following the combined LPS and hypoxia treatments. Plasma tumour necrosis factor-alpha and interleukin-6 concentrations were increased after LPS treatment with and without hypoxia, but not by hypoxia alone. In contrast, plasma cortisol concentrations were increased after both stressors.

CONCLUSIONS

These results show that the brain of young lambs readily responds to physiological stress by increased production of allopregnanolone. This response may protect the developing brain from the cytotoxicity following hypoxic and infectious episodes.

Chronic endotoxin exposure causes brain injury in the ovine fetus in the absence of hypoxemia

OBJECTIVE

Intrauterine infection has been linked to brain injury in human infants, although the mechanisms are not fully understood. We recently showed that repeated acute exposure of preterm fetal sheep to bacterial endotoxin (lipopolysaccharide [LPS]) results in fetal hypoxemia, hypotension, increased systemic proinflammatory cytokines, and brain damage, including white matter injury. However, it is not clear whether this injury is caused by reduced cerebral oxygen delivery or inflammatory pathways independent of hypoxia. The aim of the present study was to determine the effects on the fetal brain and placenta of a chronic intrauterine inflammatory state, induced by LPS infusion into the fetal circulation, a model that did not cause hypoxia.

METHODS

At 0.65 of term, eight catheterized fetal sheep received intravenous infusions of LPS (5 to 15 mug) over 5 days; control fetuses received saline. Fetal physiologic responses were monitored throughout the infusion. Fetal brain and placental tissues were examined histologically 6 days after the conclusion of the infusion.

RESULTS

LPS infusions did not result in physiologically significant alterations to fetal blood gases or mean arterial pressure; however, plasma proinflammatory cytokine levels were elevated. Following LPS exposure there was no difference in fetal body or brain weights (P >.05); placental weight was reduced (P <.05), consistent with reduced placentome cross-sectional area (P <.05). In the cerebral hemispheres subcortical white matter injury was present in six LPS-exposed fetuses and included axonal damage, microgliosis, oligodendrocyte injury, and increased beta amyloid precursor protein (beta-APP) expression.

CONCLUSIONS

Chronic, systemic exposure of the fetus to LPS resulted in fetal brain damage in the absence of hypoxemia or hypotension, although the resulting injury was less severe than following repeated acute exposure.

Activation of NF-κB transcription factor in the preterm ovine brain and placenta after acute LPS exposure

Intrauterine infection may be causally related to inflammation and injury of the fetal brain, however the mechanisms by which this occurs are unclear. We have investigated whether nuclear factor (NF)-kappaB, a transcription factor for proinflammatory cytokines, is activated in the fetal brain after acute LPS-exposure. At 95 days of gestation (term = approximately 147 days), 5 fetuses received a single intravenous bolus dose of LPS (1 microg/kg); 6 fetuses served as controls. Fetal blood samples were taken hourly for 6 hr post LPS-exposure to assess physiological status. Ewes and fetuses were then euthanased, placental and brain tissue examined histologically, and NF-kappaB activation assessed in several regions of the fetal brain using an electromobility shift assay (EMSA). Oxidative stress was measured using lipid peroxidation and 8-isoprostane biochemical assays and brain cytokine concentrations analysed by enzyme linked immunosorbent assay (ELISA). LPS-exposed fetuses (relative to controls) were hypoxemic and the haematocrit and lactate levels had increased. In the brains of LPS-exposed fetuses compared to controls, NF-kappaB binding activity was elevated in the hippocampus and the thalamus/basal ganglia; 8-isoprostane levels were elevated overall (P < 0.05) in the parietal/occipital/temporal lobes and thalamus/basal ganglia. TNF-alpha and IL-6 concentrations were not elevated, however, there was a tendency for an elevation of IFN-gamma concentrations in the thalamus/basal ganglia. IFN-gamma concentration was elevated (P < 0.05) in the plasma 4 hr after LPS-exposure. In the placenta, NF-kappaB binding activity was increased (P < 0.05). We conclude that acute systemic administration of LPS leads to increased binding activity of NF-kappaB subunits in specific regions of the fetal brain and in the placenta, but that there is no clear-cut relationship between this elevation and vulnerability to endotoxic damage.

Intestinal exposure to a parasite antigen in utero depresses cellular and cytokine responses of the mucosal immune system

The response of the mucosal immune system of 4-6-week old lambs to viable Trichostrongylus colubriformis larvae was compared in two groups of animals, one exposed to T. colubriformis antigen and the other to saline while in utero. Exposure to larval antigen two-thirds of the way through gestation resulted in significant reduction in the frequency of jejunal goblet cells and of ileal eosinophils, CD 1b(+) antigen-presenting cells and CD4(+), CD5(+) and CD8(+) cells. However, it resulted in a significant increase in the jejunal CD8(+) response to postnatal challenge. The expression of the cytokines TNF-alpha and IL-1 beta in the ileum, and of jejunal NSE, was significantly reduced by in utero exposure, whereas those of jejunal TNF-alpha and ileal TGF-beta were increased. The observed changes in cellular and cytokine responses to challenge with viable larvae, in those lambs previously exposed in utero, indicated that the intestinal mucosal immune system remains susceptible to down-regulation until considerably later in foetal development than is the case for other components of the immune system.

White matter injury after repeated endotoxin exposure in the preterm ovine fetus

Intrauterine infection has been linked to neurologic injury in preterm infants. However, a reproducible model of white matter injury in the preterm fetus in a long gestation species that can be monitored in utero is currently unavailable. Thus, our objective was to determine the effects of bacterial endotoxin (lipopolysaccharide, LPS) on physiologic and inflammatory responses and brain structure in the preterm ovine fetus. At 0.7 of gestation, six catheterized fetuses received three to five intravenous injections of LPS (1 micro g/kg) over 5 d; seven fetuses served as controls. Fetal responses were monitored and brain tissue examined 10-11 d after the initial LPS injection. After LPS on d 1 and 2, fetuses became transiently hypoxemic and hypotensive and blood IL-6 levels were increased, but these responses were smaller or absent after subsequent LPS exposures. Neural injury was observed in all LPS-exposed fetuses, most prominently in the cerebral white matter. Injury ranged from diffuse subcortical damage to periventricular leukomalacia, and in the brainstem the cross-sectional area of the corticospinal tract was reduced by 30%. Thus, repeated exposure of the preterm ovine fetus to LPS causes neuropathology resembling that of cerebral palsy and provides a robust model for exploring the etiology, prevention, and treatment of white matter damage.

Identification of monoclonal antibodies that cross-react with cytokines from different animal species

Eleven monoclonal antibodies specific for ovine, bovine and human cytokines were investigated by flow cytometry for cross-reactivities with cytokines produced by peripheral blood mononuclear cells (PBMCs) from sheep, cattle, goat, swine, horse, dog, mink, rabbit and human. Four antibodies specific for IL-4, IL-8, IFN-gamma and TNF-alpha cross-reacted with cytokines from a majority of the species investigated. These antibodies can be applied to flow cytometric studies of cytokine production by PBMCs from several veterinary species. Another five antibodies specific for IL-2, IL-6, GM-CSF and IFN-gamma (two antibodies) cross-reacted weakly and with a variable number of animal species. These antibodies could in certain situations be useful in flow cytometry. In a number of cases the immunological cross-reactivities were confirmed by Western blot analyses. Overall, the results of this study will remedy some of the lack of species-specific anti-cytokine antibodies in veterinary research.

Characterisation of a monoclonal antibody to carp IL-1beta and the development of a sensitive capture ELISA

A carp IL-1beta gene was identified from a subtraction hybridisation technology based cDNA library from activated carp leucocytes. This gene was cloned into pQE vector carrying 6xHis tag and the protein was expressed. Recombinant IL-1beta was used to produce hybridomas specific for carp IL-1beta. Monoclonal antibodies were purified by affinity column and a sandwich ELISA for IL-1beta was developed with a detection limit of 10 ng of the recombinant protein. Using the capture ELISA, the presence of native IL-1beta in culture supernatant of PHA-stimulated leucocytes from carp was identified, which was confirmed by SDS-PAGE and Western blot. Since IL-1beta is known to stimulate proliferation of T & B cells and macrophages, its ability to stimulate proliferation of carp leucocytes was studied using tritiated thymidine. The recombinant protein was found to significantly stimulate proliferation of head kidney and spleen cells from carp.

Anti-ovine interleukin-1beta monoclonal antibody immunotherapy in an ovine model of gram-negative septic shock

OBJECTIVE

To investigate the efficacy of an anti-ovine interleukin-1beta monoclonal antibody to ameliorate pathophysiological derangements and improve survival in an ovine model of gram-negative septic shock.

DESIGN

Prospective, placebo-controlled, interventional study (24-hr study period).

SETTING

University hospital animal research laboratory.

SUBJECTS

Ten awake, mature female sheep.

INTERVENTIONS

Seven milligrams per kilogram of intravenous anti-ovine interleukin-1beta immunoglobin G1 monoclonal antibody (anti-interleukin-1beta group, n = 5) or equivalent amount of protein (5% human albumin; control group, n = 5) was infused over 1 hr (time-zero minus 1 hr to time-zero) and followed by an intravenous LD100 live Escherichia coli infusion (time-zero to time-zero plus 1 hr). Normal saline, maintenance and boluses to maintain baseline filling pressures, and gentamicin, 3 mg/kg intravenous, at time-zero plus 2 and time-zero plus 13 hrs.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic and oxygen transport indexes as well as hematological, biochemical, cytokine (interleukin-1beta, tumor necrosis factor-alpha), and endotoxin measurements were performed at baseline (time-zero minus 1 hr), on completion of the monoclonal antibody/placebo (time-zero) and E. coli (time-zero plus 1 hr) infusions, and at multiple time points thereafter (time-zero plus 1.5 hrs to time-zero plus 24 hrs). Baseline data were not different between the treatment groups. From time-zero plus 1.5 hrs onward, in the anti-interleukin-1beta group, there was a sustained increase in mean arterial pressure, decreased peripheral vasodilation, and an attenuated metabolic acidosis, relative to the control group (p < or = .01, repeated-measures analysis of variance). Predicted percentage increases in mean arterial pressure and systemic vascular resistance index relative to the control group were 35% and 40%, respectively. Resuscitation fluid requirements were also decreased: anti-interleukin-1beta group, 4.1 +/- 2.9 mL x kg(-1) x hr(-1); control group, 10.6 +/- 1.8 mL x kg(-1) x hr(-1) (p < or = .01, Student's t-test). Survival was not different (anti-interleukin-1beta group, 40%; control group, 0%; p > .01, log-rank test).

CONCLUSIONS

Adjunctive therapy with anti-ovine interleukin-1beta monoclonal antibody in ovine gram-negative septic shock was associated with improved hemodynamic performance. However, the beneficial effects were incomplete and survival was not significantly improved.

Local immune responses to influenza antigen are synergistically enhanced by the adjuvant ISCOMATRIX

The peripheral (draining) lymph node, as the primary site of immune induction, determines the course of systemic responses to an injected antigen. Lymphatic duct cannulation procedures in sheep were used to investigate local immunoreactivity to human influenza virus antigen (Flu ag) admixed with the adjuvant ISCOMATRIX (IMX). Compared to Flu ag or IMX alone, the co-administration of Flu ag and IMX (Flu ag+IMX) synergistically enhanced a number of immunological responses (lymphocyte and blast migration from the node, antigen-specific antibody levels and IL6 output in efferent lymph, and antigen-induced proliferation in cultured efferent lymph cells). Together, these results demonstrate that IMX is an immune modulator, and that lymphatic duct cannulation procedures may be used to evaluate antigen/adjuvant combinations for vaccine development.

Evidence for activin A and follistatin involvement in the systemic inflammatory response

The inflammatory cascade is a multifactorial process regulated by interwoven cytokine and growth factor networks. This review summarizes the emerging evidence that implicate activin A and follistatin in inflammatory processes. Our recent studies have determined that activin A is released early in the cascade of circulatory cytokines during systemic inflammatory episodes, roughly coincident with tumour necrosis factor (TNF)-alpha and before interleukin (IL)-6 and follistatin. The source(s) of this activin A are not yet established, but prime candidates are monocytes/macrophages, other immune cell types or vascular endothelial cells. Clinical data are limited, but activin beta(A) subunit mRNA or activin A protein is elevated in inflammatory bowel diseases and inflammatory arthropathies, and circulating concentrations of follistatin are elevated in patients with sepsis. In more mechanistic approaches, in vitro studies show that activin A can have both pro- and anti-inflammatory actions on key inflammatory mediators such as TNFalpha, IL-1beta and IL-6. Furthermore, there is emerging understanding of how the intracellular signaling pathway for activin A, incorporating Smads, may interact with and be modulated by other key regulatory cytokines and growth factors.

Prostaglandins mediate the endotoxin-induced suppression of pulsatile gonadotropin-releasing hormone and luteinizing hormone secretion in the ewe

Five experiments were conducted to test the hypothesis that PGs mediate the endotoxin-induced inhibition of pulsatile GnRH and LH secretion in the ewe. Our approach was to test whether the PG synthesis inhibitor, flurbiprofen, could reverse the inhibitory effects of endotoxin on pulsatile LH and GnRH secretion in ovariectomized ewes. Exp 1-4 were cross-over experiments in which ewes received either flurbiprofen or vehicle 2 weeks apart. Jugular blood samples were taken for LH analysis throughout a 9-h experimental period. Depending on the specific purpose of the experiment, flurbiprofen or vehicle was administered after 3.5 h, followed by endotoxin, vehicle, or ovarian steroids (estradiol plus progesterone) at 4 h. In Exp 1, flurbiprofen reversed the endotoxin-induced suppression of mean serum LH concentrations and the elevation of body temperature. In Exp 2, flurbiprofen prevented the endotoxin-induced inhibition of pulsatile LH secretion and stimulation of fever, reduced the stimulation of plasma cortisol and progesterone, but did not affect the rise in circulating tumor necrosis factor-alpha. In Exp 3, flurbiprofen in the absence of endotoxin had no effect on pulsatile LH secretion. In Exp 4, flurbiprofen failed to prevent suppression of pulsatile LH secretion induced by luteal phase levels of the ovarian steroids progesterone and estradiol, which produce a nonimmune suppression of gonadotropin secretion. In Exp 5, flurbiprofen prevented the endotoxin-induced inhibition of pulsatile GnRH release into pituitary portal blood. Our finding that this PG synthesis inhibitor reverses the inhibitory effect of endotoxin leads to the conclusion that PGs mediate the suppressive effects of this immune/inflammatory challenge on pulsatile GnRH and LH secretion.

Characterisation of monoclonal antibodies to ovine interleukin-6 and the development of a sensitive capture ELISA

A purified recombinant ovine (rOv) interleukin-6 (IL-6) was used to generate specific murine monoclonal antibodies (mAbs) and a polyclonal rabbit antisera to this cytokine. From the 31 initial hybridoma cell lines generated, three stable clones were established which secreted mAbs to rOvIL-6, as judged by a direct enzyme-linked immunosorbent assay (ELISA) and Western blotting. Their specificity was further confirmed by demonstrating that none of the mAbs recognised any of the six other irrelevant recombinant ovine cytokines tested by direct ELISA. All three mAbs displayed cross-reactivity with human and African green monkey IL-6 as demonstrated by direct ELISA and Western blotting. In contrast, the polyclonal antibodies only cross-reacted with bovine IL-6 and not with either of the human or monkey homologues. By combining a mAb with the polyclonal antisera a sensitive, IL-6-specific, capture ELISA was developed that had a sensitivity of 150 pg/ml. This detection system was unequivocally validated by demonstrating that native OvIL-6 could be detected in efferent lymph draining from a stimulated popliteal lymph node. In addition, one of the mAbs was shown to allow the detection of OvIL-6 by intracellular cytokine staining and flow cytometry.

Antibody and cytokine responses in efferent lymph following vaccination with different adjuvants

The cannulated efferent lymph node in sheep was used to examine the effect of different adjuvants on the antibody and cytokine responses following sub-cutaneous vaccination with a recombinant Taenia ovis antigen (45 W). Vaccination with Quil A elicited relatively higher levels of IgM than did IFA or Al(OH)3. In general, 45 W specific IgG1 and IgG2 titres were higher and maintained for longer periods of time in lymph from sheep vaccinated with IFA and lower and shorter lived in animals which received the Al(OH)3 based vaccine. Interferon-gamma was present within one day in efferent lymph from all sheep which received the Quil A formulation and in only one of the three sheep that received the IFA formulation. GM-CSF was only detected in lymph from sheep vaccinated with the IFA formulation. IL-8 was present in lymph prior to vaccination and only animals which received the Quil A formulation had increased levels of IL-8 after vaccination. Neither of the inflammatory cytokines IL-1 beta and TNF alpha were detected in efferent lymph from any animals in this study. This paper highlights the potential of the lymphatic cannulation model for investigations of the in vivo action of adjuvants.

Analysis of ovine IL-1 beta production in vivo and in vitro by enzyme immunoassay and immunohistochemistry

A monoclonal antibody (mAb) specific for ovine IL-1 beta was produced and, in conjunction with a polyclonal rabbit antiserum, used to develop a sensitive enzyme immunoassay (EIA) for ovine interleukin 1 beta (IL-1 beta). The mAb neutralised the activity of recombinant ovine IL-1 beta (rOvIL-1 beta) and native OvIL-1 in an ovine thymocyte proliferation assay. However, it did not neutralise the biological activity of rOvIL-1 beta in the murine NOB1/CTLL assay. The mAb did not react with rOvIL-1 alpha, IL-2, IL-4, IL-8, tumor necrosis factor-alpha, gamma-interferon or recombinant human IL-1 beta in indirect EIA. Immunohistological staining of activated alveolar macrophages and frozen lymph node sections sections demonstrated that the mAb detected IL-1 beta secreted by ovine macrophages (CD11c-positive). The EIA was highly sensitive, detecting less than 50 pg ml-1 of rOvIL-1 beta and low levels of native IL-1 beta in supernatants from lipopolysaccharide-stimulated macrophages. The EIA did not detect heat-inactivated IL-1 beta.

Effects of purified bovine whey factors on cellular immune functions in ruminants

The immunomodulatory properties of bovine milk and whey have long been documented. The recent advance of whey protein fractionation technology has now allowed us to study the immunobiological properties of some highly purified components of whey, with a view to exploiting their possible industrial and biomedical applications. The effects of fractionated bovine whey proteins on cellular immune responses were therefore examined using a panel of in vitro assays. Both lactoferrin (LF) and lactoperoxidase (LP) were found to inhibit proliferation and interferon-gamma (IFN-gamma) production of ovine blood lymphocytes in response to mitogenic stimulation. However, their effects in a combined fraction or in whey protein concentrate (WPC) were either diminished or eliminated. LF and LP had no effect on lipopolysaccharide (LPS)-induced ovine blood lymphocyte proliferation, production of interleukin-1 beta (IL-1 beta) and tumour necrosis factor-alpha (TNF alpha) by ovine bronchoalveolar lavage (BAL) macrophages, major histocompatibility complex (MHC) Class II antigen expression by ovine BAL macrophages and bovine natural killer (NK) cell activity. However, alpha-lactalbumin (alpha LA) exhibited an enhancing effect on IL-1 beta production. It is noteworthy that as bovine whey fractions become progressively more purified, their modulatory effects on the immune response also become more clear-cut. The effects of LF, LP and alpha LA may be eliminated by their combination in whey or by other minor components of whey. Further investigation of industrial applications for whey proteins of high purity is warranted.

Leukocyte and cytokine accumulation in the ovine teat and udder during endotoxin-induced inflammation

The accumulation of leukocytes, ovine serum albumin and the cytokines interleukin-1 beta(IL-1 beta), tumour necrosis factor-alpha(TNF-alpha), interleukin-8 (IL-8), granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon-gamma(IFN-gamma) was studied during endotoxin-induced inflammation in lactating and dry ovine udders, and in the teat cisterns of dry ewes after surgical closure of the passage between the teat and udder cisterns. Samples were taken before infusion and hourly up to 10 h after infusion of 0.1, 1 or 10 micrograms of endotoxin, or infusion of pyrogen-free saline (PFS) as a control. Rectal temperatures were measured. A significant dose- and time-dependent accumulation of leukocytes, mainly neutrophils, was observed in the lactating udders and in the teat cisterns. In the dry udders, the leukocyte accumulation was significant for time but not for dose. Peak numbers of cells were reached at 3-4 h in the dry udders and in the teat cisterns, but not until 10 h after infusion in the lactating udders. The changes in the ovine serum albumin concentrations mostly paralleled changes in leukocyte numbers. A role was indicated for TNF-alpha, IL-8 and GM-CSF, but not for IL-1 beta and IFN-gamma, during endotoxin-induced inflammation in the ovine udder. Release of TNF-alpha, IL-8 and GM-CSF was most prominent in lactating udders, peaking at 2 or 3 h after infusion, but was also detected in dry udders and teat cisterns. Detectable levels of IL-1 beta and IFN-gamma were occasionally found in all three groups.

Inflammation-induced changes in the phenotype and cytokine profile of cells migrating through skin and afferent lymph

In the present study, we have localized cytokine-secreting cells within an ectoparasite-induced inflammatory lesion and monitored the phenotype and cytokine profile of cells migrating from the inflammatory lesion to the local draining lymph node via the afferent lymphatics. Interleukin (IL)-8-producing cells were first detected in skin within 6 hr of infection, with increased numbers observed at 24 and 48 hr post infection. While these cells were concentrated within the neutrophil influx, adjacent to disrupted epidermis; they were also found scattered throughout the surrounding dermis in areas where significant cellular infiltration was not apparent. IL-1 alpha- and IL-1 beta-producing cells could not be detected until 24 hr after infection and were restricted to areas of intense neutrophil accumulation. Concurrent with the onset of inflammation was a threefold increase in the total number of cells migrating through the draining afferent lymph. This increase in cellularity was due primarily to increased migration of CD4 and gamma delta T cells. Cytokine mRNA synthesis by migrating afferent lymph cells was examined by reverse transcription-polymerase chain reaction (RT-PCR) analysis of RNA extracted prior to, and at regular intervals during the course of the inflammatory response. IL-1 beta and IL-8, but not IL-1 alpha or IL-6 mRNA, was detected in migrating afferent lymph cells. Tumour necrosis factor (TNF)-alpha-specific mRNA was present in migrating afferent lymph cells at all time points both prior to, and following infection. Soluble IL-8 protein, but not IL-1 alpha, IL-1 beta or TNF-alpha protein, could be detected in lymph, with the amount of IL-8 detected increasing as the infection progressed. mRNA coding for cytokines associated with T-cell activation, such as IL-2, IL-4 or interferon (IFN)-gamma, was also detected in migrating cells, although the cytokine profiles of different experimental animals were extremely variable.

T cell cytokines and disease prevention

Until recently, work on cytokines has been dominated by the use of murine or human molecules. In the last 5 years we have seen a rapid expansion in the production of bovine, ovine and porcine cytokine reagents. cDNA clones, recombinant proteins and monoclonal antibody probes are not available for a wide variety of cytokines from veterinary species. One of the most interesting recent proposals in immunology has been the division of T helper cells into two classes. Th1 cells have been characterised by the production of gamma-interferon, interleukin (IL)-2, tumour necrosis factor-beta (lymphotoxin-alpha) and the ability to mediate delayed-type hypersensitivity responses, and Th2 cells by their production of IL-4, IL-5, IL-6 and IL-10 and the ability to stimulate production of mast cells, eosinophils and IgE. An important issue for us is to determine whether polarisation of T helper cells to Th1 or Th2 occurs in veterinary species. This paper will attempt to review the status of the Th1 and Th2 debate for sheep, cattle and pigs. It will also discuss the potential for the use of cytokines in modulating the type of immune response following vaccination. By incorporation of particular cytokines into vaccine formulations or the inhibition of production of specific cytokines it may be possible to redirect the nature of the immune response to a particular antigen.

Local cell traffic and cytokine production associated with ectoparasite infection

This paper reviews recent advances in our understanding of changes in local cellular traffic and cytokine synthesis that occur as a result of infection of sheep with the ectoparasite Lucilia cuprina. Changes in the cellular composition and cytokine profile of infected skin and draining afferent and efferent lymph were assessed using standard approaches and, in addition, a variety of techniques that have only recently become available as a result of advances in ruminant cytokine biology. These include cytokine-specific immunoassay, reverse transcription PCR (RT-PCR) and immunohistology. The initial acute inflammatory response was characterised by the infiltration of polymorphonuclear cells followed by selected lymphocyte subsets into discrete areas adjacent to the site of infection. Analysis of cytokine expression in skin prior to and following infection provided a molecular basis for the observed cellular events. Both cellular and molecular events within the skin were reflected within draining afferent lymph providing a basis for the conclusion that events within the skin (other than antigen uptake and transport) may influence events within the draining node and thus the outcome of the immune response to the parasite. Analysis of cellular and molecular changes in efferent lymph during infection suggested initiation of antigen-specific immunity.

Modulation of immune responses by bovine beta-casein

The present reports the influence of bovine beta-casein on in vitro and in vivo immune responses. Bovine beta-casein showed an inhibitory effect on ovine neutrophil chemotaxis but had an enhancing effect on superoxide production by neutrophils. In response to mitogenic stimulation, the proliferative response of both T and B lymphocytes was significantly enhanced by beta-casein. While beta-casein had no significant effects on IFN gamma production by ovine blood lymphocytes, and TNF alpha production and MCH Class II antigen expression by ovine bronchoalveolar macrophages, it enhanced IL-1 beta production by the macrophages, beta-casein also had no influence on bovine NK cell activity against a virally-infected cell line. Interestingly, beta-casein was found to reduce the adjuvant effect of matrix immune stimulating complexes (ISCOM) on anti-ovalbumin antibody response in mice when given intramuscularly. Taken together, the results suggest that bovine beta-casein had selective modulating effects in vitro on both innate and adaptive immune responses in ruminants, whereas systemic administration of beta-casein, that might have a depressive effect on adjuvant activity, requires further study.

Plasma follistatin concentrations increase following lipopolysaccharide administration in sheep

1. The effect of inflammation induced by lipopolysaccharide (LPS) injection on plasma follistatin (FS) concentrations was investigated. 2. Plasma FS and tumour necrosis factor-alpha concentrations increase following LPS administration in ewes. 3. The rise in FS is similar, but more sustained, to that previously observed after surgery. 4. These results indicate a possible functional link between FS, inflammation and the acute-phase response.

Macrophage function in deer

Macrophage inflammatory and immune functions were characterised in red deer (cervus elaphus), for use as a model for natural infection with bovine tuberculosis. Highly enriched populations of deer macrophages were obtained from 14 day cultures of plastic-adherent peripheral blood mononuclear cells. Cervine macrophages produced superoxide anion in response to respiratory burst stimuli (serum-opsonised zymosan and phorbol myristic acetate), but nitric oxide production could not be detected under the conditions tested. The lysosomal enzymes acid phosphatase and lysozyme were detected at the intercellular and extracellular level. Stimulation with bacterial lipopolysaccharide extract (Escherichia coli LPS) enhanced the production of superoxide and acid phosphatase with a peak increase in activity observed after 2h. Production of interleukin 1 (IL-1) and tumour necrosis factor (TNF), determined using cytokine-sensitive cell lines and mRNA analysis (Northern blotting), indicated maximal secretion of both cytokines after 24 h stimulation with LPS, preceded by a peak in message accumulation at 2-6 h post-stimulation. Cervine macrophages stimulated proliferative responses in T cell-enriched lymphocyte populations derived from the peripheral blood of autologous animals that had been primed to mycobacterial antigens (Mycobacterium bovis Bacille Calmette-Guerin, BCG). Macrophages were able to stimulate responses after pulsing with particulate (BCG) or soluble (purified protein derivative) mycobacterial antigens. These results indicate that macrophage inflammatory and immune responses in red deer are similar to those in other mammalian species, and that macrophages may play an important role in resistance to mycobacterial infection.

Cloning and characterisation of an ovine interleukin-10-encoding cDNA

Expression of the interleukin 10-encoding (IL-10) mRNA by ovine (ov-) cells, in response to mitogenic stimulation, was assessed by Northern blot and polymerase chain reaction (PCR) analyses using a human (hu) IL-10 cDNA probe and oligodeoxyribonucleotide primers based on homologous regions of the human and murine IL-10 cDNA sequences. A 315-bp cDNA generated by the PCR analysis was cloned and used to screen a lipopolysaccharide-stimulated alveolar ov-macrophage cDNA library. The full-length ov-cDNA sequence isolated translates to a protein of 177 amino acids (aa) with a predicted 18-aa leader sequence and molecular mass of 20,165 Da. Expression in a mammalian system demonstrated that the ov-cDNA encoded a protein with the expected IL-10 biological activity. Both recombinant huIL-10 and supernatants from COS cells transfected with an expression vector containing the ovIL-10 cDNA inhibited production of IL-1 and tumour necrosis factor-alpha by ov-alveolar macrophages. Genomic DNA analysis indicated ovIL-10 exists as a single gene within the ov-genome.