Genetic and phenotypic selection affect natural (auto-) antibody reactivity of chickens

Levels of Circulating IgM and IgY Natural Antibodies in Broiler Chicks: Association with Genotype and Farming Systems

Naturally occurring antibodies (NAbs), which are major components of innate immunity, exist in circulation under healthy conditions without prior antigenic stimulation and are able to recognize both self- and non-self-constituents. The present study aimed at identifying potential immunological differences between commercial fast- and slow-growth broilers (n = 555) raised in conventional and free-range systems, respectively, through the use of the specificity, isotypes and levels of circulating NAbs. The possible beneficial effect of oregano-based dietary supplementation was also evaluated. To this end, serum IgM and IgY NAbs against self- (actin and DNA) and non-self- antigens (trinitrophenol and lipopolysaccharide) were measured by ELISA and further correlated with genotype, season and performance. Significantly higher levels of IgM NAbs against all antigens were found in slow-growth compared to fast-growth broilers. IgM NAb levels were also significantly increased in dietarily supplemented slow-growth broilers versus those consuming standard feed. Moreover, significantly elevated levels of anti-DNA IgY NAbs were found in fast-growth compared to slow-growth broilers, whereas the opposite was observed for anti-LPS IgY NAbs. Multivariate linear regression analysis confirmed multiple interactions between NAb levels, genotype, season and performance. Overall, serum NAbs have proven to be valuable innovative immunotools in the poultry industry, efficiently differentiating fast-growing versus slow-growing broilers, and dietary supplementation of plant extracts can enhance natural immunity.

Relation between redox potential and natural antibody levels in goat kid serum

The redox potential and the natural antibody (NAb) levels are parameters commonly tested to verify the physiological response to stressful situations determined by farming conditions or research needs. In this paper, the redox potential, assessed by different spectrophotometric methods, was related to NAb levels together with total immunoglobulin (tot-Ig) levels in goat kid serum. Reactive oxygen metabolites (ROMs) and ceruloplasmin (CP) oxidase activity were significantly associated with NAb-IgG and NAb-IgM. Nitric oxide metabolites (NOx) and total thiol levels (TTLs) were significantly related to NAb-IgM and tot-IgM, and with NAb-IgG, respectively. A tendency was shown between ROMs and tot-IgM, and between CP and tot-IgM, where, however, the significance levels were above the cut-off values. Total oxidant status (TOS), total antioxidant activity (TAA), determined by the ABTS-based method, the ferric reducing ability of plasma (FRAP), and free radical scavenging activity (FRSA) were associated with neither NAb nor tot-Ig. The obtained results are discussed in light of the possible linkage between the (anti)oxidant status and the innate immune system in goats.

Effects of early nutrition and sanitary conditions on antibody levels in early and later life of broiler chickens

Immune maturation of broiler chickens may be affected by management, such as early life feeding strategy (early versus delayed nutrition) or by low or high sanitary conditions (LSC versus HSC). We compared systemic maternal (MAb), natural (NAb), natural auto- (NAAb), and antigen specific antibody (SpAb) levels (IgM, IgY) between broilers (n = 48 per treatment) that received early (EN) or delayed nutrition for 72 h (DN) housed in either low (LSC) or high sanitary conditions (HSC) between 7 and 35 d of age. We found minimal interactions between feeding strategy and sanitary conditions. At 7 d of age, broilers receiving EN compared with DN, had elevated levels of IgM binding keyhole limpet hemocyanin (KLH), phosphoryl-conjugated ovalbumin (PC-OVA), and muramyl dipeptide (MDP), whereas effects of feeding strategy diminished at later ages. In LSC compared with HSC broilers, levels of NAb agglutinating RRBC and sheep red blood cells (SRBC) were already elevated from 14 d of age onwards. At 33 d of age, antibody levels (NAb, NAAb, anti-LPS, anti-MDP) were all elevated in LSC, compared with HSC broilers, for both IgM and IgY, but not IgM against KLH. Western blotting revealed different binding patterns of NAAb against chicken liver homogenate, which may indicate that the NAAb repertoire is affected by antigenic pressure. Our data suggest that antibody levels are affected for an important part by environmental conditions (feeding strategy and sanitary conditions), but minimally by their interaction. However, it remains to be further studied whether the enhanced levels of antibodies as initiated by EN and LSC contribute to enhanced resistance to infectious diseases.

Current Understanding of Natural Antibodies and Exploring the Possibilities of Modulation Using Veterinary Models. A Review

Natural antibodies (NAb) are defined as germline encoded immunoglobulins found in individuals without (known) prior antigenic experience. NAb bind exogenous (e.g., bacterial) and self-components and have been found in every vertebrate species tested. NAb likely act as a first-line immune defense against infections. A large part of NAb, so called natural autoantibodies (NAAb) bind to and clear (self) neo-epitopes, apoptotic, and necrotic cells. Such self-binding antibodies cannot, however, be considered as pathogenic autoantibodies in the classical sense. IgM and IgG NAb and NAAb and their implications in health and disease are relatively well-described in humans and mice. NAb are present in veterinary (and wildlife) species, but their relation with diseases and disorders in veterinary species are much less known. Also, there is little known of IgA NAb. IgA is the most abundant immunoglobulin with essential pro-inflammatory and homeostatic properties urging for more research on the importance of IgA NAb. Since NAb in humans were indicated to fulfill important functions in health and disease, their role in health of veterinary species should be investigated more often. Furthermore, it is unknown whether levels of NAb-isotypes and/or idiotypes can and should be modulated. Veterinary species as models of choice fill in a niche between mice and (non-human) primates, and the study of NAb in veterinary species may provide valuable new insights that will likely improve health management. Below, examples of the involvement of NAb in several diseases in mostly humans are shown. Possibilities of intravenous immunoglobulin administration, targeted immunotherapy, immunization, diet, and genetic modulation are discussed, all of which could be well-studied using animal models. Arguments are given why veterinary immunology should obtain inspiration from human studies and why human immunology would benefit from veterinary models. Within the One Health concept, findings from veterinary (and wildlife) studies can be related to human studies and vice versa so that both fields will mutually benefit. This will lead to a better understanding of NAb: their origin, activation mechanisms, and their implications in health and disease, and will lead to novel health management strategies for both human and veterinary species.

Transfer of natural auto-antibodies via egg yolk in chickens divergently selected for natural antibodies binding keyhole limpet hemocyanin

Barcodes of natural auto-antibody (NAAb) profiles based on staining intensity of isotypes binding numbers of self-(tissue) antigen fragments were suggested as parameters for immune diversity, and related to genetic background and health status in man, rodents and poultry. Here, hens, eggs and hatchlings from chicken lines divergently selected and bred for high (H line) or low (L line) total natural antibodies (NAb) levels in plasma binding keyhole limpet hemocyanin (KLH) at 16 weeks of age were tested for their NAAb repertoire binding chicken liver homogenate (CLH) fragments using quantitative Western immunoblotting. The aims of this study were 1. to detect line differences between the H and L line adult hens, eggs and hatchlings for the IgM and IgG isotypes binding CLH fragments, 2. study the presence of NAAb of both isotypes in yolk and albumen, as well as in hatchlings to detect a maternal NAAb transfer route via the egg to the hatchling, and 3. study whether new self-antigen binding isotypes and idiotypes are present in the hatchling. NAAb binding CLH fragments were found in plasma of adult hens (both IgM and IgG), in yolk (IgG only), and hatchlings (mostly IgG, but low levels of IgM). Auto-profiles of IgM showed homogeneity, while IgG profiles were heterogenic between individual hens and individual hatchlings. Significant higher levels as indicated by staining intensity and number of stained CLH fragments were found in plasma of hens genetically selected for high levels of NAb binding KLH. Lines could be clustered based on their auto-profiles indicating that profiles of self-binding IgM and IgG antibodies are genetically based. Visual comparison, clustering and correlation of hens and their hatchlings showed similarities for the IgG, but not the IgM isotype, indicating maternal transfer of IgG NAAb via the yolk. The IgM profile in the hatchlings on the other hand might represent neonatal self-binding antibody formation. As a consequence, hatchlings initially depend for self-binding antibodies on maternal IgG provision during early life.

Genetic aspects of auto-immune profiles of healthy chickens

Auto-antibody profiles binding liver antigens differed between chicken lines divergently selected for specific antibody responses to SRBC, and were affected by ageing suggesting both genetic and environmental effects. Presence and levels of IgM and IgG antibodies binding chicken liver cell lysate (CLL) fragments in plasma at 5 weeks of age from 10 individual full sibs and their parents from 5 H_srbc and 5 L_srbc line families was studied to reveal genetic relations. Non-genetic maternal effects were studied by comparing auto-antibody profiles of 36 weeks old hens from 2 other unrelated lines with the profiles from their chicks at hatch. IgM and IgG antibodies from parents and progeny from both H_srbc and L_srbc lines bound CLL fragments. Significant line and generation differences and their interactions were found for both isotypes. Higher staining of CLL fragments was usually found for H_srbc line birds. Lines were clustered by auto-antibody profiles, but staining by birds of both lines in both generations was very individual for IgG and IgM. The current data with full sibs therefore not supported a genetic basis for auto-antibody profiles. IgG but not IgM auto-antibody profiles of chicks correlated with maternal auto-antibody profiles. The results suggest that the auto-antibody repertoire of healthy chickens is largely stochastically initiated and may be affected by environmental challenges during ageing, but genetic mechanisms may underlie staining intensity of individual bound CLL fragments. The present results suggest that identification of fragments or profiles to be used at early age for genetic selection for health traits is not feasible yet. Secondly, the IgM profile of neonatal chickens seems non-organised independent of the maternal profile, but the neonatal IgG profile is much more related with the maternal profile. Consequences of these findings for disease susceptibility or breeding for optimal health are discussed.

Evaluation of the effects of dexamethasone-induced stress on levels of natural antibodies in immunized laying hens

Natural antibodies (NAb) are an important humoral component of innate immunity, playing a pivotal role as first line of defence against pathogens even without prior antigen-specific activation or antigen-driven selection. The levels of NAb in plasma of young laying hens were explored in more detail and identified 2,4,6-trinitrophenyl bovine serum albumin (TNP-BSA), as the non-self antigen showing the highest levels of IgΥ- and IgM-NAb. Subsequently, the relation between specific antibody (SpAb) levels and NAb levels, and the effect of dexamethasone (DEX)-induced stress on the acquired Ab response and on NAb levels were examined. According to obtained results, the affinity of NAb and SpAb, measured using the thiocyanate elution method, resulted higher in SpAb than in NAb. After stress induction, IgM-NAb and SpAb levels showed a transient decrease, whereas the levels of IgΥ-NAb were not changed. Moreover, statistical analysis showed positive correlations between IgΥ- and IgM-NAb levels and between IgM-NAb and SpAb levels that are lost as stress has been induced, whereas no correlation was observed between IgΥ-NAb and SpAb levels, neither before nor after the DEX-administration. This indicates that IgM-NAb assessment could be a valid tool to estimate the potential of the acquired Ab response and that the dexamethasone-induced stress condition causes depression of IgM-NAb levels and the acquired Ab response, but it has no evaluable effects on IgΥ-NAb levels.

Exploring early and late Toxoplasma gondii strain RH infection by two-dimensional immunoblots of chicken immunoglobulin G and M profiles

Toxoplasma gondii is an intracellular apicomplexan parasite infecting warm-blooded vertebrate hosts, with only early infection stage being contained with drugs. But diagnosis differencing early and late infection was not available. In the present investigation, 2-dimensional immunobloting was used to explore early and late infections in chickens. The protein expression of T. gondii was determined by image analysis of the tachyzoites proteome separated by standard-one and conventional two-dimentional gel polyacrylamide electrophoresis (2D- PAGE). Pooled gels were prepared from tachyzoites of T. gondii. A representative gel spanning a pH range of 3-10 of the tachyzoite proteome consisted of 1306 distinct polypeptide spots. Two-dimensional electrophoresis (2-DE) combined with 2-DE immunoblotting was used to resolve and compare immunoglobulins (Igs) M & G patterns against Toxoplasma gondii strain RH (mouse virulent strain). Total tachyzoite proteins of T. gondii were separated by two-dimensional gel electrophoresis and analyzed by Western blotting for their reactivity with the 7 and 56 days post-infection (dpi) SPF chicken antisera. Different antigenic determinant patterns were detected during analysis with M and G immunoglobulins. Of the total number of polypeptide spots analyzed (1306 differentially expressed protein spots), 6.97% were identified as having shared antigenic polypeptide spots on immunoblot profiles with IgG and IgM antibodies regardless the time after infection. Furthermore, some of the immunoreactive polypeptide spots seemed to be related to the stage of infection. Interestingly, we found natural antibodies to toxoplasmic antigens, in addition to the highly conserved antigenic determinants that reacted with non-specific secondary antibody; goat anti-chicken IgG antibodies conjugated with horseradish peroxidase. In conclusion, unique reactive polypeptide spots are promising candidates for designation of molecular markers to discriminate early and late chicken infection.

Natural (auto)antibodies in calves are affected by age and diet

BACKGROUND

Natural autoantibodies (N(a)ab) were found in every species tested so far, and are likely important in maintaining homeostasis.

OBJECTIVES

(1) To determine N(a)ab in Bos taurus calves, (2) evaluate effects of diet and age on N(a)ab binding repertoires in calves, and (3) delineate bovine liver cell lysate (BLL) antigens related with variation in rumen score and body weight.

ANIMALS AND METHODS

Effects of age and diet on staining of BLL fragments by IgM and IgG antibodies in serum samples collected at 20 or at 26 weeks of age from bull calves either fed a restricted or ad libitum diet were analyzed using quantitative Western blotting. Correlations between fragments stained and grouping of calves were done by Principal Component Analysis (PCA). Redundancy analysis (RDA) was done to relate rumen score and body weight variation at slaughter at 27 weeks of age with stained BLL fragments.

RESULTS

In sera from all calves IgM and IgG antibodies binding BLL antigens were found. Corresponding fragments were stained, but quantitative differences in staining intensities were related to diet and age for both IgM and IgG. PCA revealed that age had a greater influence than diet on BLL fragment staining. RDA suggested that staining by IgM or IgG of specific BLL fragments was related with variation in rumen score and body weight.

CONCLUSIONS AND CLINICAL IMPORTANCE

Analyses of N(a)ab in serum could be a potential tool to estimate the health status of cattle, and be used to evaluate effects of husbandry practices.

Age and genetic selection affect auto-immune profiles of chickens

Specificity, antibody isotype distribution and levels, of natural autoantibodies (NAAb) may be potential informative parameters for immune mediated natural disease resistance, immune modulation, and maintenance of physiological homeostasis. In a previous study we detected IgM and IgG antibodies to liver antigens in plasma from 1 year old chickens. Auto-immune profiles directed towards liver antigens differed between chicken lines divergently selected for specific antibody responses to sheep red blood cells. In the present study we measured the presence and typed levels and antibody isotypes (IgG and IgM) of NAAb binding the 'auto-antigen' complex chicken liver cell lysate (CLL) in plasma samples obtained from chickens at 5 weeks and at 1-year of age, respectively, by quantitative western blotting. Extensive staining patterns of plasma antibodies binding CLL were found for both isotypes and at both ages in all birds. At both ages, IgM and IgG bound similar numbers of CLL antigens, which remained almost constant for IgM, whereas the number of IgG stained bands in time was enhanced. Significant differences of binding patterns of NAAb (stained antigen fragments of CLL and staining intensity) were detected between the three different chicken lines at both ages and between both ages, and lines could be clustered on the basis of their auto-antibody profile. The present results indicate that analysis of the plasma NAAb repertoire of poultry like in mammals could provide a way of distinguishing differences of immune competence (as reflected by the selection criterion of antibody responses) between individuals and lines, and could provide tools to select individual birds for health and other traits. The age-dependency of the auto-immune profile suggest that such profiles may also reflect immune maturation, which should be taken into account when relating an auto-immune profile with other traits.