Does the range of motion in the bovine interphalangeal joints change with flooring condition? A pilot study using biplane high-speed fluoroscopic kinematography.

This study had 2 objectives. The first objective was to investigate motion patterns and the range of motion of the bovine proximal and distal interphalangeal joints on concrete during the stance phase. The second objective was to determine whether the range of motion and the locomotive stability of the interphalangeal joints differ on concrete and 3 different commercially available rubber mats (Karera, Kura, and Pedikura; Kraiburg Elastik GmbH & Co. KG, Tittmoning, Germany). Biplane high-speed fluoroscopic kinematography (72 ± 2.5 kV and 112.5 ± 12.5 mA, refresh rate 500 frames per second, shutter 0.5 ms) was applied to record 1 stance phase of the right forelimb of 2 Holstein Friesian heifers (15 mo old, 440 ± 10 kg; ± standard deviation) on each flooring. Three-dimensional digital animations were generated with a marker-supported manual animation technique based on the recordings and computer tomographic bone models. The mean maximum range of motion of each of the 4 interphalangeal joints in terms of flexion/extension, abduction/adduction, and internal/external rotation were calculated as well as the mean number of local extrema as a measure of stability during the stance phase. The main degree of freedom in all interphalangeal joints was flexion and extension with a range of motion of 17.7 to 25.9°. The second largest degree of freedom differed between abduction/adduction (7.7-10.0°) and internal/external rotation (6.5-9.6°) depending on the joint. Remarkably, although smaller, these extrasagittal directions still contribute to the overall motion to a considerable degree. In addition, the interphalangeal joints of the lateral digit showed a tendency to move less during the stance phase than their medial counterparts. Comparing concrete to the rubber mats, the interphalangeal joints tend to have to cover a larger range of motion on concrete with the exception of the distal interphalangeal joint in terms of flexion/extension. The unyielding surface of concrete seems to force the flexible parts of the animal-ground-interaction into extended motion. Furthermore, there tends to be more instability in all 3 degrees of freedom in all 4 joints on concrete, implying a greater effort of the soft tissues to achieve a balanced motion. Detailed biomechanical research contributes to the development of adequate flooring systems by evaluating the mechanical strain on claws and joints and working toward lameness prevention and thus animal welfare.

Effect of different flooring types on pressure distribution under the bovine claw - an ex vivo study.

BACKGROUND: Mechanical interactions between hard floorings and the sole of bovine claws can be reasonable to cause traumatic claw lesions. In this ex vivo study, the direct kinetic impact of concrete and three types of rubber mats on the sole of dairy cattle claws was analyzed. In order to apply uniform loads, isolated distal hind limbs of adult Holstein Friesian dairy cows were functionally trimmed according to the Dutch method and attached to a load applicator. Kinetic data were recorded using a thin, foil-based pressure measurement system (Hoof™ System, Tekscan®). RESULTS: On concrete, the load distribution between the lateral and medial claw was less balanced than on the rubber floorings. The loaded area was significantly smaller on concrete (32.2 cm2) compared to all rubber mats (48.3-58.0 cm2). Average pressures (Pav) and maximum pressures (Pmax) were significantly higher on concrete (Pav 44.7 N/cm2; Pmax 130.3 N/cm2) compared to the rubber floorings (Pav 24.9-29.7 N/cm2; Pmax 71.9-87.2 N/cm2). Pressure peaks occurred mainly in plantar and abaxial parts of the lateral claw and in apical and plantar regions of the medial claw. Load distribution displayed a widely unloaded slope region, but considering the pressure distribution under the claw, none of the zones showed a generally lower pressure exposure. CONCLUSIONS: Altogether, rubber floorings lead to a significant mechanical relief of the sole compared to concrete. Furthermore, relevant differences between the tested rubber mats could be determined. Therefore the used system may be applied to compare further flooring types.

Validation of 2 noninvasive, markerless reconstruction techniques in biplane high-speed fluoroscopy for 3-dimensional research of bovine distal limb kinematics.

Lameness severely impairs cattle's locomotion, and it is among the most important threats to animal welfare, performance, and productivity in the modern dairy industry. However, insight into the pathological alterations of claw biomechanics leading to lameness and an understanding of the biomechanics behind development of claw lesions causing lameness are limited. Biplane high-speed fluoroscopic kinematography is a new approach for the analysis of skeletal motion. Biplane high-speed videos in combination with bone scans can be used for 3-dimensional (3D) animations of bones moving in 3D space. The gold standard, marker-based animation, requires implantation of radio-opaque markers into bones, which impairs the practicability for lameness research in live animals. Therefore, the purpose of this study was to evaluate the comparative accuracy of 2 noninvasive, markerless animation techniques (semi-automatic and manual) in 3D animation of the bovine distal limb. Tantalum markers were implanted into each of the distal, middle, and proximal phalanges of 5 isolated bovine distal forelimbs, and biplane high-speed x-ray videos of each limb were recorded to capture the simulation of one step. The limbs were scanned by computed tomography to create bone models of the 6 digital bones, and 3D animation of the bones' movements were subsequently reconstructed using the marker-based, the semi-automatic, and the manual animation techniques. Manual animation translational bias and precision varied from 0.63 ± 0.26 mm to 0.80 ± 0.49 mm, and rotational bias and precision ranged from 2.41 ± 1.43° to 6.75 ± 4.67°. Semi-automatic translational values for bias and precision ranged from 1.26 ± 1.28 mm to 2.75 ± 2.17 mm, and rotational values varied from 3.81 ± 2.78° to 11.7 ± 8.11°. In our study, we demonstrated the successful application of biplane high-speed fluoroscopic kinematography to gait analysis of bovine distal limb. Using the manual animation technique, kinematics can be measured with sub-millimeter accuracy without the need for invasive marker implantation.

Prevalence of enteroparasitic infections and related hormonal and immunological repercussions that may compromise students' physical performance.

The aim of this study was to evaluate the prevalence of enteroparasitic infections in students and their hormonal and immunological repercussions on physical development. Students of basic education of both sexes were evaluated. Parasitological stool tests were performed using the Hoffman and Kato-Katz methods. The students were divided into two groups: a control group (negative parasitological examination, N=25) and an infected group (positive parasitological test, N=25). Anthropometric variables (height, weight, and BMI), concentrations of hormones (melatonin and cortisol), cytokine/chemokine levels (IL-1ß, IL-6, IL-8, IL-10, IL-12, IL-17 and TNF-α) and physical performance (aerobic capacity, upper- and lower-limb muscle strength and abdominal performance) were evaluated. The prevalence of parasitic infection among the students was 7.98%. No anthropometric differences were observed among the groups. IL-2 and TNF-α levels were higher and IL-8 levels were lower in serum from students who were positive for parasitic infection. Serum from students who were positive for parasitic infection showed higher levels of melatonin than that from parasitenegative students. No differences were observed in cortisol levels. Students who were positive for parasitic infection presented greater lower-limb strength and lower abdominal performance than parasite-negative students. In the parasitic infection group, IL-12 was positively correlated with melatonin. In the parasitic infection group, IL-8 showed a positive correlation with aerobic capacity, while IL-17 and TNF-α showed a positive correlation with abdominal performance. These data suggest that parasitic infections determine the profile of inflammatory cytokines and that melatonin may be involved in the control of this process to minimize tissue damage. Additionally, students' difficulty in practising physical exercises can be an indication of enteroparasitic infection.

Validation of biplane high-speed fluoroscopy combined with two different noninvasive tracking methodologies for measuring in vivo distal limb kinematics of the horse.

REASON FOR PERFORMING STUDY: Biplane high-speed fluoroscopy is a new method for gait analysis of the equine distal extremity. This is the first study validating the noninvasive tracking possibilities (Autoscoping and Scientific Rotoscoping) taking equine anatomy into account. OBJECTIVES: To determine the resolution with which Autoscoping and Scientific Rotoscoping depict motion of the equine phalanges in comparison to the invasive gold standard marker-based registration. STUDY DESIGN: Comparative ex vivo study. METHODS: In 5 distal extremities of slaughtered ponies, 3 or 4 tantalum beads with 1 mm diameter were implanted in each of the proximal, middle and distal phalangeal bones. Three-dimensional models of the bones were reconstructed using computed tomographic data (120 kV, 50 mA, slice thickness 1 mm, increment 0.5). The beads were digitally removed from the bone models. Biplane fluoroscopic videos were taken at 69.5 ± 3.5 kV, 102.5 ± 22.5 mA, 500 frames/s and 0.5 ms shutter speed. The 5 specimens were moved in the trial field of the biplane fluoroscopic setup in a step-like motion (simulation of landing, main stance phase, lift-off). Marker-based registration, Autoscoping and Scientific Rotoscoping were carried out. For statistical analysis agreement was computed as percentiles, mean and s.d. RESULTS: The medians of Scientific Rotoscoping ranged from 0.16 to 0.66 mm in translations and 0.43 to 2.78° in rotations, while values for Autoscoping were 0.13-0.70 mm and 0.28-2.39° respectively. With 2 exceptions, all differences between methods were statistically significant. Scientific Rotoscoping is more time efficient than Autoscoping and results in smaller maximum errors. MAIN LIMITATIONS: The experimental set-up was specifically designed to accommodate in vivo requirements. Autoscoping was not manually corrected but rather expected to work automatically. CONCLUSIONS: It is possible to noninvasively apply both Autoscoping and Scientific Rotoscoping for gait analysis of the equine phalanges with high precision. The summary is available in Chinese - see supporting information.

Prevalence of enteroparasitic infections and related hormonal and immunological repercussions that may compromise students’ physical performance

@#The aim of this study was to evaluate the prevalence of enteroparasitic infections in students and their hormonal and immunological repercussions on physical development. Students of basic education of both sexes were evaluated. Parasitological stool tests were performed using the Hoffman and Kato-Katz methods. The students were divided into two groups: a control group (negative parasitological examination, N=25) and an infected group (positive parasitological test, N=25). Anthropometric variables (height, weight, and BMI), concentrations of hormones (melatonin and cortisol), cytokine/chemokine levels (IL-1β, IL-6, IL-8, IL-10, IL-12, IL-17 and TNF-α) and physical performance (aerobic capacity, upper- and lower-limb muscle strength and abdominal performance) were evaluated. The prevalence of parasitic infection among the students was 7.98%. No anthropometric differences were observed among the groups. IL-2 and TNF-α levels were higher and IL-8 levels were lower in serum from students who were positive for parasitic infection. Serum from students who were positive for parasitic infection showed higher levels of melatonin than that from parasitenegative students. No differences were observed in cortisol levels. Students who were positive for parasitic infection presented greater lower-limb strength and lower abdominal performance than parasite-negative students. In the parasitic infection group, IL-12 was positively correlated with melatonin. In the parasitic infection group, IL-8 showed a positive correlation with aerobic capacity, while IL-17 and TNF-α showed a positive correlation with abdominal performance. These data suggest that parasitic infections determine the profile of inflammatory cytokines and that melatonin may be involved in the control of this process to minimize tissue damage. Additionally, students’ difficulty in practising physical exercises can be an indication of enteroparasitic infection.

Cellular immune responses and cytokine production in BALB/c and C57BL/6 mice during the acute phase of Angiostrongylus costaricensis infection.

In our experimental study we were able to show that the contrasting outcome of Angiostrongylus costaricensis infection in C57BL/6 and BALB/c mice, in respect of morbidity and mortality, can be explained by divergent cellular immune responses and a different cytokine pattern in each strain. In BALB/c mice (i.e. those with high mortality), the initial high proliferation of ConA or LPS stimulated spleen cells dropped to very low levels after 2 weeks post-infection (p.i.), whereas in C57BL/6 mice (i.e. those with low mortality), only a minor reduction in lymphoproliferative responses after mitogenic stimulation was observed. The specific proliferation of spleen cells after stimulation with A. costaricensis adult worm antigen remained low in BALB/c mice throughout the experiment, but showed an augmented proliferation in C57BL/6 mice, especially from 2 weeks p.i. onwards. The mitogen-induced production of Th2-type cytokines (IL-4, IL-5, IL-6, IL-10) in spleen cell cultures remained low in BALB/c mice until 4 weeks p.i., but production of Th1-type cytokines (IL-2, IFN-gamma) was highly elevated at 14 and 28 days p.i. In C57BL/6 mice, an upregulated and balanced production of both Th1- and Th2-type cytokines was measured during the course of infection. In summary, a polarization of the immune response towards cellular hyporesponsiveness and a predominantly Th1 cytokine profile was observed in A. costaricensis infected BALB/c mice, which may contribute to pathogenesis and increased morbidity.

Immuno-epidemiology of Schistosoma mansoni infections in endemic populations co-infected with soil-transmitted helminths: present knowledge, challenges, and the need for further studies.

This article reviews studies on epidemiological and immunological interactions between Schistosoma mansoni and soil-transmitted helminths (STH) in co-infected patients from endemic areas. In Brazil, co-infections with schistosomes and intestinal nematodes, such as Ascaris lumbricoides, Trichuris trichiura and the hookworms, are still common, especially in poor rural areas. Important factors in the co-occurrence of different helminth species are favorable environmental conditions supporting intermediate hosts and the survival of larval stages outside the human host, widespread poverty, and low levels of hygiene and sanitation. The few existing epidemiological surveys on helminth co-infections in humans indicate positive associations between schistosomes and STH, which means high prevalences of mixed infections, as well as higher intensities of infection in co-infected patients. However, these positive interactions appear to depend on the number of different helminth species present and on the intensity of infection in each individual. For the humoral immune response in co-infected patients, much cross-reactivity in antibody responses against antigenic preparations from schistosomes and STH is observed. Data on cellular immune responses in multiply infected patients are still scarce and additive effects on the cellular reactivity and the down-modulation of cytokines are proposed.

Stage-specific immune responses in human Necator americanus infection.

We describe how hookworms interact with their human hosts by comparing lymphocyte phenotyping, proliferative responses, and cytokine and chemokine secretion patterns in adults who are either mono-infected with Necator americanus or egg-negative controls resident in an area of high transmission in Brazil. Cellular immune responses against crude hookworm antigen extracts from different developmental stages were evaluated simultaneously. Principal component analysis (PCA) was used to reduce the standardized immune responses. Random effects multivariate regression was then used to investigate whether principal components (PC) differ between the two groups once potential confounders and effect modifiers have been accounted for. Although hookworm patients had reduced percentages of T and B cells, they had higher levels of activated CD4(+) T and CD19(+) B cells. This state of 'immune activation' coincided with lower proliferative responses, especially to third-stage larval antigen. Cytokine levels in mono-infected adults were also lower and characterized by a mixed Th1/Th2-type profile. Excretory/secretory antigen from adult worms was a potent modulator of the immune response, resulting in diminished TNF-alpha and IL-10 secretion in peripheral blood mononuclear cells (PBMC) from hookworm infected patients. We propose that the longevity of hookworms in their human hosts results from a stage-specific, down-modulation of the immune response.

Comparative immunology of human and animal models of hookworm infection.

Hookworm infection is a major cause of disease burden for animals and humans. Over the past years, the use of animal models in hookworm infections has been driven by the search of new anthelminthic therapies and, especially, vaccine development. These studies also contributed to the advance of knowledge on immunity to hookworms, offering new insights to understand the nature of this parasitic infection. In this article, we will summarize the essential features of the immune response in the two major animal models of hookworm infections (dog and hamster) and then consider its implication for the human immune response.

Cellular responses and cytokine production in post-treatment hookworm patients from an endemic area in Brazil.

Human hookworm infections are distributed widely in tropical areas and have a significant impact on host morbidity and human health. In the present study, we investigated the cellular responsiveness and cytokine production in peripheral blood mononuclear cells (PBMC) from Necator americanus-infected schoolchildren who had recently received chemotherapy, and compared them with non-infected endemic controls. Hookworm patients and treated, egg-negative individuals showed a lower cellular reactivity against phytohaemagglutinin (PHA) and hookworm antigen when compared with egg-negative endemic controls. The baseline production of proinflammatory tumour necrosis factor-alpha (TNF-alpha) in PBMC from infected patients and treated, egg-negative individuals was elevated. On the other hand, PHA- or hookworm antigen-induced interleukin (IL)-12 and interferon (IFN)-gamma secretion was higher in endemic controls than in hookworm patients, who either continued egg-positive or were egg-negative after treatment. Also, PBMC from endemic controls secreted more IL-5 and IL-13 than the other patient groups. Opposite to that, the spontaneous as well as the antigen-driven IL-10 secretion was lower in endemic controls when compared with the other groups. In summary, patently hookworm-infected as well as egg-negative treated patients disclosed an elevated spontaneous cellular secretion of proinflammatory TNF-alpha, a prominent secretion of regulatory Th2-type IL-10 and an impaired production of IL-12, IFN-gamma, IL-5 and IL-13.

Experimental Angiostrongylus costaricensis infection in mice: immunoglobulin isotype responses and parasite-specific antigen recognition after primary low-dose infection.

Immunoglobulin isotype responses and parasite-specific antigen recognition were investigated in experimental Angiostrongylus costaricensis infection in two different mouse strains. Even in a low-dose infection with third-stage larvae (L3), BALB/c mice showed high mortality until 28 days postinfection (p.i.) in association with a low patency rate in surviving animals. On the other hand, low mortality and a high rate of patent infection was observed in C57BL/10 mice. Parasite-specific IgM, total IgG, and IgG subclasses against crude adult-worm antigen (AcAg) rose in both groups of mice from day 14 onward, with IgG and IgG1 being significantly elevated in BALB/c mice at 21 and 28 days p.i., respectively. For total IgE, significantly elevated concentrations were detected at 14 days p.i. in BALB/c mice as compared with C57BL/10 mice. A. costaricensis-specific antigen recognition by total IgG, IgG1, or IgG2a was similar in both mouse strains, intensifying from 3 to 4 weeks p.i., with recognition of immunodominant AcAg ranging between 80 and 210 kDa. This study provides evidence that in BALB/c and C57BL/10 mice, immunoglobulins, with the possible exception of IgE and IgG1, do not decisively contribute to the outcome of a primary A. costaricensis infection with respect to immunopathogenesis or parasite permissiveness.

The role of nitric oxide in the innate resistance to microfilariae of Litomosoides sigmodontis in mice.

Nitric oxide (NO) has been shown to be an important effector mechanism in the defence against various pathogens, including filariae. The production of NO, as well as H2O2, is induced by the Th1 cytokine IFN-gamma. Therefore, the microfilariae (mf) of filarial nematodes, which are known to elicit the release of IFN-gamma, may be a target of NO release. In this study, we found that mf of the filarial species Litomosoides sigmodontis were resistant to the attack of H2O2, but vulnerable to NO exposure in vitro by a chemical NO donor, as well as activated macrophages. Adult worms were considerably less affected by exposure to NO. In-vivo production of NO following injection of mf, in this and previous studies, suggested a central role in the defence to filariae. However, neither pharmaceutical inhibition of nitric oxide synthesis, nor genetic knockout of the gene for inducible nitric oxide synthase (iNOS), abrogated resistance to circulating mf in mice. Interestingly, however, iNOS-KO mice showed higher interleukin (IL)-2 responses and lower IL-10 production, compared to their wild-type counterparts. In conclusion, despite its effectiveness in vitro and the observed production of NO by ex vivo cells following infection, nitric oxide seems not to be an important factor in elimination of mf of L. sigmodontis in vivo. However, it may have a regulatory role in the immune response.

Long-term observations on mouse strains experimentally infected with Angiostrongylus costaricensis.

BALB/c and C57BL/6 mice were experimentally infected with Angiostrongylus costaricensis and the parasitic parameters and antibody response during the acute and chronic phases of infection were analyzed. Following administration of six third-stage larvae (L3), there was no significant difference in the mean worm recovery or mean larval output. Coinciding with the maturation of worms in infected animals and with the egg output in mesenteric arteries, a strong increase in the humoral immune response was observed in both mouse strains. This response was characterized by a hypergammaglobulinemia, with a predominance of IgA and IgG1 during the acute phase of infection, and IgG1 and total IgE during the patent and post-patent periods. Significantly higher levels of IgM, IgG and IgG1 were found in BALB/c mice compared with C57BL/6 mice. On the other hand, a significantly higher concentration of IgA was detected at 6 and 7 weeks post-infection in C57BL/6 mice compared with BALB/c mice. Specific IgE could not be detected in any of the mouse strains. Our results suggest that immunoglobulins, mainly IgG1, contribute to the outcome of a primary A. costaricensis infection with respect to the period of patency and to mortality during the chronic phase.

Angiostrongylus costaricensis infection in C57BL/6 mice: MHC-II deficiency results in increased larval elimination but unaltered mortality.

During experimental Angiostrongylus costaricensis infections in several inbred mouse strains, genetic factors as well as different cytokine secretion patterns have recently been shown to play a role in the outcome of infection in terms of morbidity and mortality, e.g. BALB/c mice show a high and C57BL/6 mice a low mortality during the acute phase of infection. In this study, C57BL/6 MHC-II knockout mice infected with A. costaricensis did not show increased mortality during the acute phase of infection when compared with wild-type mice. Furthermore, MHC-II knockout mice showed a strongly diminished parasite-specific humoral and cellular immune response, which can be explained by the nearly complete lack of CD4+ T cells in the periphery. This defect in MHC-II genes, the lack of CD4+ T cells, and the resulting cellular and humoral unresponsiveness resulted in a three times higher output of first-stage larvae in feces compared with wild-type animals. The results indicate that during experimental A. costaricensis infection a parasite-specific immune response, directed via MHC-II molecules and CD4+ T cells, is not essential for the survival of C57BL/6 mice during the acute phase of infection, whereas the elimination of first-stage larvae seems to be regulated by a MHC-II- and CD4+ T-cell-dependent mechanism.

Litomosoides sigmodontis: dynamics of the survival of microfilariae in resistant and susceptible strains of mice.

Litomosoides sigmodontis in the BALB/c mouse is the only model of filariasis which allows the observation of the complete development in an immunocompetent mouse. In this study, we injected microfilariae (mf) intravenously, as well as into the pleural cavity, the site of natural release of mf from adult female worms, and followed the kinetics of elimination within the host. In susceptible BALB/c mice, mf circulated at high levels in the blood. In contrast, in C57BL/6 mice, which are refractory to full development, mf were eliminated rapidly from the peripheral blood. However, 6 days after intrapleural injection, viable larvae could be found in the pleural cavity and lung capillaries of both susceptible and resistant strains. The numbers of mf in the pleural cavity and lung capillaries in individual mice were significantly correlated, but not dependent on strain or peripheral microfilaraemia. Thus, although C57BL/6 mice showed enhanced production of nitric oxide by pleural exudate cells and a faster change in the numbers of circulating leukocytes after injection, rapid killing of mf by cell or nitric oxide-mediated mechanisms were not the reason for the different outcome. Furthermore, 3 h after iv injection, only a small percentage of mf could be recovered from the peripheral circulation, indicating the presence of a reservoir for mf containment. In conclusion, injected mf showed disparate dynamics of persistence within susceptible and resistant hosts, which is similar to the disparate outcome of natural infections with L. sigmodontis. This difference became obvious within 1 day after injection. The lung capillary system plays obviously a crucial part in regulation of microfilaremia. Our model also provides a possible means to explain frequent cases of occult infections in human filariasis.

Detection of the acute phase of abdominal angiostrongyliasis with a parasite-specific IgG enzyme linked immunosorbent assay.

Angiostrongylus costaricensis may cause intestinal lesions of varied severity when it accidentally infects man in Central and South America. First-stage larvae have never been detected in stools. Therefore, a parasite-specific IgG ELISA was evaluated for the determination of the acute phase of infection. The specificity and the sensitivity of the immunoassay was shown to be 76.2% and 91.1%, respectively. Eight serum samples taken from patients with histopathological diagnosis, at different time points (3 to 15 months) after surgical treatment, showed a sharp and early decline in antibody reactivity. The titration of anti-A. costaricensis antibodies has proved to be a useful method for the diagnosis of acute abdominal angiostrongyliasis.

Regulatory effects of Th1-type (IFN-gamma, IL-12) and Th2-type cytokines (IL-10, IL-13) on parasite-specific cellular responsiveness in Onchocerca volvulus-infected humans and exposed endemic controls.

The present study investigated in vitro the regulatory effects of T helper 1 (Th1)-type (interferon-gamma, IFN-gamma; interleukin-12, IL-12) and Th2-type cytokines (IL-10, IL-13) on Onchocerca volvulus-specific cellular reactivity in onchocerciasis patients, and in exposed endemic control individuals presenting no clinical and parasitological signs of disease. In both patients and controls, addition of IL-10 dose-dependently depressed O. volvulus antigen (OvAg)-specific cellular proliferation, and peripheral blood mononuclear cells (PBMC) from patients who were more sensitive to the suppressive effect of IL-10 than those from endemic controls. However, neutralization of IL-10 by specific antibody did not reverse cellular hyporesponsiveness. In contrast to the inhibitory effects of IL-10, exogenous IL-12 and IL-13 augmented PBMC proliferative responses to OvAg both in patients and controls (P<0. 01) and neutralizing of IL-12 or IL-13 significantly decreased OvAg-specific proliferation in both groups. Exogenous IFN-gamma did not activate OvAg-specific proliferative responses in patients, but anti-IFN-gamma antibodies abolished cellular reactivity to OvAg. Antibody to IL-10 increased (P<0.05) OvAg-specific production of IL-5, IL-12 and IFN-gamma, and inversely, anti-IFN-gamma enhanced IL-10 (in patients only) and IL-5 and IL-13 in both patients and controls. Neutralization of IL-12 activated OvAg-specific production of IL-10, IL-2 and IFN-gamma. In conclusion, despite of an overproduction of IL-10, which suppressed cellular reactivity in patients and control individuals, OvAg-specific cellular responses were activated in vitro by exogenous supplementation with IL-12 and IL-13, and cytokine neutralization experiments confirmed that distinct type 1 and type 2 T helper cytokines cross-regulate expression and magnitude of O. volvulus-specific cellular responsiveness in humans.

Prenatal immune priming in onchocerciasis-onchocerca volvulus-specific cellular responsiveness and cytokine production in newborns from infected mothers.

This study investigated the effect of maternal Onchocerca volvulus infection on humoral and cellular responsiveness in newborn children and their mothers. Onchocerca volvulus-specific IgG isotypes and IgE were significantly elevated in infected mothers and their infants. One year post partum, O. volvulus-specific IgG4 was strongly reduced in children of infected mothers, while IgG1 responses weakened only slightly. Umbilical cord mononuclear blood cells (UCBC) and peripheral blood cells (PBMC) from mothers proliferated in response to phytohaemagglutinin (PHA), concanavalin A (Con A), and the bacterial antigens streptolysin-O (SL-O) or purified protein derivative (PPD). UCBC from neonates born to O. volvulus-infected mothers responded lower (P < 0.01) to Con A (at 5 micrograms/ml), PPD (at 10 and 50 micrograms/ml) and O. volvulus-derived antigens (OvAg) (at 35 micrograms/ml), and in parallel, a diminished cellular reactivity (P < 0.01) by PBMC was observed to OvAg in mothers positive for O. volvulus. Several Th1-type (IL-2, IL-12, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha)) and Th2-type (IL-4, IL-5, IL-10, IL-13) cytokines were secreted by UCBC and PBMC in response to OvAg, bacterial SL-O and PHA. OvAg did not stimulate IL-2 and none of the mitogens or antigens induced production of IL-4 in neonates. In response to OvAg, substantially elevated (P < 0.01) amounts of IFN-gamma were produced by UCBC from newborns of O. volvulus-infected mothers. UCBC secreted low levels of IL-5 and IL-13, while higher amounts of IL-10 were found (P < 0. 01) in newborns from onchocerciasis-free mothers. In conclusion, maternal O. volvulus-infection will sensitize in utero parasite-specific cellular immune responsiveness in neonates and activate OvAg-specific production of several Th1- and Th2-type cytokines.

The diverse expression of immunity in humans at distinct states of Onchocerca volvulus infection.

This study examined the development and persistence of immunity in humans presenting defined states of Onchocerca volvulus infection, i.e. in exposed endemic control individuals without microfilaridermia and clinical disease, in patients with patent or post-patent onchocerciasis, and in patients concurrently infected with Mansonella perstans. Onchocerca volvulus antigen (OvAg)-specific cellular reactivity was significantly diminished in microfilariae (mf)-positive patients, while the highest reactivity was measured in exposed but mf-negative endemic controls, those being free of any clinical signs of onchocercal disease. In patients who became post-patent, responses to OvAg were significantly augmented, but did not approach entirely the magnitude observed in endemic controls. In onchocerciasis patients with concurrent mansonelliasis, cellular unresponsiveness to OvAg persisted, even when mf of O. volvulus were eliminated permanently by repeated ivermectin therapy. Cells from mf-positive onchocerciasis patients produced significantly less interferon-gamma (IFN-gamma) (P < 0.01) and interleukin-5 (IL-5) (P < 0.05) in response to OvAg than those taken from endemic controls or post-patent individuals in whom IFN-gamma and IL-5 production was similarly high. In contrast, both OvAg-driven as well as spontaneous IL-10 secretion was higher in mf-positive patients than in endemic controls or post-patent cases. In all individuals examined, serological recognition of OvAg by immunoglobulins was dominated by IgG4; in mf-positive patients OvAg of 205,000-12,000 molecular weight (MW) were strongly bound. In post-patent individuals, and similarly in endemic controls. OvAg recognition by IgG4 varied from intense (with numerous antigens being recognized) to weak or absent antigen binding. Significantly elevated OvAg-specific IgG isotypes were measured in mf-positive onchocerciasis patients in comparison with endemic controls or post-patent individuals (with the exception of IgG3). IgG1, IgG2 and IgE were higher, but IgG4 was lower in endemic controls compared with post-patent onchocerciasis patients. The ratios of IgG4/IgG1 differed (P < 0.001) between endemic controls and mf-positive or post-patent onchocerciasis patients, with IgG4/IgG1 ratios of R < 3.0 being characteristic for endemic controls and post-patent O. volvulus infection. In conclusion, this cross-sectional immunoepidemiological investigation showed that distinct states of O. volvulus infection correlate with a particular cellular and humoral immune response. The mf-free condition appeared to be associated with a vigorous parasite-specific cellular reactivity and a particular cytokine production profile, while concurrent M. perstans infection depressed OvAg-specific cellular responsiveness. Antibody responses, in all likelihood, reflected the intensity and state of infection, and not the degree of acquired immunity protective against parasite aggregation.