Immunology discovers physiology

Is AMR in Dairy Products a Threat to Human Health? An Updated Review on the Origin, Prevention, Treatment, and Economic Impacts of Subclinical Mastitis

Background

Bovine mastitis is the most frequent and costly illness impacting dairy herds worldwide. The presence of subclinical mastitis in dairy cows has an impact on the decreased output of milk and milk quality, culling of affected cows, mortality rate, as well as mastitis-related treatment expenses, generating significant financial loss to the dairy industry. The pathogenic bacteria invade through the mammary gland, which then multiply in the milk-producing tissues causing infection, and the presence of pathogenic bacteria in milk is concerning, jeopardizes human health, and also has public health consequences. Intervention to promote herd health is essential to protect public health and the economy.

Results

This review attempts to provide an overview of subclinical mastitis, including mastitis in different species, the effect of mastitis on human health and its pathogenic mechanism, the prevalence and incidence of subclinical mastitis, and current preventive, diagnostic, and treatment methods for subclinical mastitis. It also elaborates on the management practices that should be followed by the farms to improve herd immunity and health.

Conclusion

This review brings the importance of the threat of antimicrobial resistance organisms to the dairy industry. Furthermore, this review gives a glimpse of the economic consequences faced by the farmers and a futuristic mastitis market analysis in the dairy industry.

Effects of medium chain triglycerides with organic acids on growth performance, fecal score, blood profiles, intestinal morphology, and nutrient digestibility in weaning pigs

Objective

This study was conducted to evaluate the effects of medium chain triglycerides (MCT) with organic acids (OA) on growth performance, fecal score, blood profiles, intestinal morphology, and nutrient digestibility in weaning pigs.

Methods

A total of 120 weaning pigs ([Yorkshire×Landrace]×Duroc) with an average body weight (BW) of 8.00±0.87 kg were assigned in five treatments considering sex and initial BW in 3 replications with 8 pigs per pen in a randomized complete block design. The experimental diets included a corn-soybean meal based basal diet with or without 0.1% or 0.2% MCT and 0.1% OA. The pigs were fed the diets for 5 weeks (phase 1, 0 to 2 weeks; phase 2, 3 to 5 weeks). A total of 15 barrows with an average BW of 12.48±0.37 kg were used to evaluate the nutrient digestibility by total collection method. The BW and feed intake were measured at the end of each phase. Blood samples and small intestine samples were collected at the end of each phase, too.

Results

Supplementing 0.1% MCT with 0.1% OA showed greater BW for week 5 and average daily gain (ADG) for overall period than control diet. Supplementing 0.1% MCT increased (p<0.05) ADG and improved (p<0.05) gain:feed ratio for phase 1. Dietary MCT and OA did not affect the fecal score and blood concentration of cortisol, immunoglobulin G, tumor necrosis factor-α, interleukin-1β (IL-1β), IL-6, and IL-10 in weaning pigs. Pigs fed the diets with 0.1% MCT had greater (p<0.05) villus height of duodenum and ileum for phase 1. Also, pigs fed the diet with 0.1% OA showed greater (p<0.05) villus height and villus height to crypt depth ratio of duodenum for phase 2. There was no significant difference in nutrient digestibility and nitrogen retention of pigs.

Conclusion

Addition of 0.1% MCT with 0.1% OA in weaning pig’s diet improved growth performance partly by enhancing intestinal morphology in weaning pigs.

An intensive milk replacer feeding program benefits immune response and intestinal microbiota of lambs during weaning

Background

Pre-weaning milk replacer (MR) feeding program is a key factor affecting the health and welfare of lambs during their weaning. Weaning stress is well known as an inducement that negatively impacts the immune system of young ruminants, whose physiological and immune state is closely linked to the community of microbiota in their intestines. This study had two objectives: 1) To evaluate the innate immune response to weaning stress at both the physiological and molecular level; 2) To investigate changes to the jejunal chyme and mucosal adhesive microbiota between the control and high plane of MR groups.

Results

In this experiment, the plasma concentrations of cortisol, norepinephrine (NE) and tumor necrosis factor-α (TNFα) were higher in the C than the H group (P < 0.05), as was the expression of pro-inflammatory cytokines such as TNFα and CXCL8 (P < 0.05) in plasma. In jejunal tissue, the expression of TLR4 and TNFα were also higher in the C group (P < 0.01); histopathology showed the H group had lower lymphocyte infiltration. In the C group, however, major pathological changes were associated with extensive infiltration of lymphocytes, eosinophils, and neutrophils. Principal component analysis indicated the lamb immune response was influenced by weaning stress and modulated by the MR treatments. 16S-rRNA sequencing was used to evaluate jejunal mucosa and chyme bacterial diversity and composition. The C group’s chyme had a greater alpha index (ACE: P = 0.095; Chao1: P = 0.085) than H group. In jejunal mucosa, the relative abundance of Plesiomonas was 4-fold higher (P = 0.017) in the C than the H group.

Conclusions

This study’s results revealed that weaning stress induced alterations to the lambs’ immune system that lasted beyond the 21 d measured, and that a long-term inflammatory response effect was evidenced by changes in their hematological and expressed pro-inflammatory cytokines. Pre-weaning with a differing MR allowance resulted in complicated biological responses and compositional changes to the lambs’ jejunal microbiota. Clearly, an intensive MR feeding program induced a milder immunity response and lower relative abundance of pathogenic bacteria when compared with the traditional feeding program.

Immune system, inflammation and nutrition in dairy cattle

Good health is essential for good performance and the welfare of dairy cows, and nutrition is an important component of good health. Health is influenced by the interaction between the innate adaptive components of the immune system and other factors, such as the local and systemic inflammatory response, which can sometimes be more harmful than useful. Therefore, for dairy cows, particularly those in the periparturient period, it is important to avoid, or reduce as much as possible, any kind of infectious, parasitic or metabolic disease and the associated inflammation. Such inflammation can impair cow performance by lowering milk yield, dry matter intake, fertility and energy efficiency, and can reduce liver function. Good nutrition is essential in maintaining a functional immune system, while also avoiding other causes of inflammation, such as tissue damage, and digestive and metabolic syndrome-related disorders. Provision of appropriate nutrients, such as antioxidants, omega-3 polyunsaturated fatty acids, conjugated linoleic acid and vitamin D can have anti-inflammatory effects. In the future, ways to reduce inflammation while maintaining a good immune defence must be developed and the susceptibility of the cow to diseases and inflammation evaluated. Ideally, we would be able to selectively breed for cows with a lower susceptibility to both diseases and inflammation.

Environmental stressors influencing hormones and systems physiology in cattle

Environmental stressors undoubtedly influence organismal biology, specifically the endocrine system that, in turn, impact cattle at the systems physiology level. Despite the significant advances in understanding the genetic determinants of the ideal dairy or beef cow, there is a grave lack of understanding of the systems physiology and effects of the environmental stressors that interfere with the endocrine system. This is a major problem because the lack of such knowledge is preventing advances in understanding gene-environment interactions and developing science-based solutions to these challenges. In this review, we synthesize the current knowledge on the nature of the major environmental stressors, such as climate (heat, cold, wind, and humidity), nutrition (feeds, feeding systems, and endocrine disruptors) and management (housing density and conditions, transportation, weaning practices). We summarize the impact of each one of these factors on cattle at the systems level, and provide solutions for the challenges.

Effects of Acanthopanax senticosus Polysaccharide Supplementation on Growth Performance, Immunity, Blood Parameters and Expression of Pro-inflammatory Cytokines Genes in Challenged Weaned Piglets

To investigate the effect of dietary Acanthopanax senticosus polysaccharide (ASPS) on growth performance, immunity, blood parameters and mRNA expression of pro-inflammatory cytokines in immunologically challenged piglets, an experiment employing 2×2 factorial arrangement concerning dietary ASPS treatment (0 or 800 mg/kg) and immunological challenge (lipopolysaccharide [LPS] or saline injection) was conducted with 64 crossbred piglets (weaned at 28 d of age, average initial body weight of 7.25±0.21 kg) assigned to two dietary ASPS treatments with 8 replicates of 4 pigs each. Half of the piglets of per dietary treatment were injected with LPS or saline on d 14. Blood samples were obtained at 3 h after immunological injection on d 14 and piglets were slaughtered to obtain spleen samples on d 21. Dietary ASPS did not affect average daily gain (ADG) (p = 0.634), average daily feed intake (ADFI) (p = 0.655), and gain:feed (p = 0.814) prior to LPS challenge. After LPS challenge, for LPS-challenged pigs those fed ASPS had higher ADG and ADFI than the non-supplemented group (p<0.05), and an interaction between LPS×ASPS was observed on the two indices (p<0.05). Dietary ASPS improved lymphocyte proliferation among saline-injected and LPS-injected pigs (p<0.05). Interaction between LPS×ASPS was also revealed on lymphocyte proliferation (p<0.05). Circulatory concentration of IgG was influenced neither by ASPS (p = 0.803) or LPS (p = 0.692), nor their interaction (p = 0.289). Plasma concentration and spleen mRNA expression of interleukin-1beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor (TNF)-α were induced to increase (p<0.05) by LPS challenge, in contrast, these indices were decreased by dietary ASPS (p<0.05), and interactions were found on these cytokines (p<0.05). For LPS-challenged pigs, dietary ASPS also reduced the circulating concentration and spleen mRNA expression of IL-1β, IL-6 as well as TNF-α (p<0.05). The interaction between LPS×ASPS was also observed on the circulating concentration of insulin-like growth factor- I, α-acid glycoprotein (α-AGP), nonesterified fatty acid, and glucose (p<0.05). The results of this study demonstrate that dietary ASPS can modulate the release of pro-inflammatory cytokines during immunological challenge, which might enable piglets to achieve better growth performance.

Getting nervous about immunity

Twenty-five years ago, immunologists and neuroscientists had little science of mutual interest. This is no longer the case. Neuroscientists now know that the first formally defined cytokine, IL-1, activates a discrete population of hypothalamic neurons. This interaction leads to the release of glucocorticoids from the adrenal gland, a hormone that has a long history in immunoregulation. Immunologists have been surprised to learn that lymphoid cells synthesize acetylcholine, the first formally recognized neurotransmitter. This neurotransmitter suppresses the synthesis of TNF. These discoveries blur the distinction of neuroscience and immunology as distinct disciplines. There are now 37 formally recognized cytokines and their receptors, and at least 60 classical neurotransmitters plus over 50 neuroactive peptides. These findings explain why both immunologists and neuroscientists are getting nervous about immunity and highlight a real need to apply integrative physiological approaches in biomedical research.

Elucidating molecular networks that either affect or respond to plasma cortisol concentration in target tissues of liver and muscle

Cortisol is a steroid hormone with important roles in regulating immune and metabolic functions and organismal responses to external stimuli are mediated by the glucocorticoid system. Dysregulation of the afferent and efferent axis of glucocorticoid signaling have adverse effects on growth, health status, and well-being. Glucocorticoid secretion and signaling show large interindividual variation that has a considerable genetic component; however, little is known about the underlying genetic variants. Here, we used trait-correlated expression analysis, screening for expression quantitative trait loci (eQTL), genome-wide association (GWA) studies, and causality modeling to identify candidate genes in porcine liver and muscle that affect or respond to plasma cortisol levels. Through trait-correlated expression, we characterized transcript activities in many biological functions in liver and muscle. Candidates from the list of trait-correlated expressed genes were narrowed using only those genes with an eQTL, and these were further prioritized by determining whether their expression was predicted to be related to variation in plasma cortisol levels. Using network edge orienting (NEO), a causality modeling algorithm, 26 of 990 candidates in liver were predicted to affect and 70 to respond to plasma cortisol levels. Of 593 candidates in muscle that were correlated with cortisol levels and were regulated by eQTL, 2 and 25 were predicted as effective and responsive, respectively, to plasma cortisol levels. Comprehensive data integration has helped to elucidate the complex molecular networks contributing to cortisol levels and thus its subsequent metabolic effects. The discrimination of up- and downstream effects of transcripts affecting or responding to plasma cortisol concentrations improves the understanding of the biology of complex traits related to growth, health, and well-being.

Need for a paradigm shift in therapeutic approaches to CNS injury

Irreversible damage to the nervous system can result from many causes including trauma, disruption of blood supply, pathogen infection or neurodegenerative disease. Common features following CNS injury include a disruption of axons, neuron death and injury, local B-cell and microglial activation, and the synthesis of pathogenic autoantibodies. CNS injury results in a pervasive inhibitory microenvironment that hinders regeneration. Current approaches to eliminate the inhibitory environment have met with limited success. These results argue for a paradigm shift in therapeutic approaches to CNS injury. Targeting CNS cells (neurons, oligodendrocytes and astrocytes) themselves may drive CNS repair. For example, our group and others have demonstrated that autoreactive antibodies can participate in aspects of CNS regeneration, including remyelination. We have developed recombinant autoreactive natural human IgM antibodies with the therapeutic potential for CNS repair in several neurologic diseases.

The stress of weaning influences serum levels of acute-phase proteins, iron-binding proteins, inflammatory cytokines, cortisol, and leukocyte subsets in Holstein calves

The purpose of our study was to investigate changes in immunological parameters induced by weaning stress (including milk restriction) in calves. Fifteen Holstein calves were subjected to weaning at 6 weeks of age. Blood samples were collected at -14, -7, -2, 1, 3, and 5 days post-weaning (DPW; 0 DPW = 42 days). Weaning caused significant (p < 0.01) increases in the neutrophil (NE):lymphocyte (LY) ratio at 5 DPW with a significant (p < 0.05) reduction of LYs. The concentration of acute-phase proteins (haptoglobin and serum amyloid A) also increased significantly (p < 0.05) at 3 and 5 DPW compared to -2 DPW. Levels of the iron-binding protein lactoferrin decreased significantly (p < 0.05) after weaning. Serum tumor necrosis factor-α and cortisol levels were elevated (p < 0.05) at 3 DPW, while those of serum interferon-γ decreased (p < 0.05) at 1 and 3 DPW compared to levels observed before weaning. Weaning significantly (p < 0.05) decreased the percentage of CD25(+) T cells in the peripheral blood. In conclusion, weaning stress affected the NE:LY ratio along with the levels of acute phase proteins, lactoferrin, cortisol, and inflammatory cytokines in the peripheral blood of calves. Weaning stress may induce an acute phase response possibly through the elevation of cortisol production and modulation of inflammatory cytokines.

Supplementation of diets for gestating sows with zinc amino acid complex and gastric intubation of suckling pigs with zinc-methionine on mineral status, intestinal morphology and bacterial translocation in lipopolysaccharide-challenged early-weaned pigs

Eighty male pigs from 20 litters were used to evaluate dietary addition of 250mg/kg of Zn from zinc amino acid complex (ZnAA) to sows during the last trimester of gestation and gastric intubation of 40mg Zn from soluble zinc methionine (ZnMet) to suckling pigs at birth and on day 7 and 14 (weaning) on small intestinal morphology, Zn status and bacterial translocation in early-weaned pigs. At weaning, pigs were challenged with an intramuscular injection of saline without or with 120microg/kg BW of lipopolysaccharide (LPS; from Escherichia coli O26:B6) and were euthanized 24h later prior to collection of intestinal lymph nodes and small intestinal sections. Zinc concentration in serum 7 days after birth and at weaning were higher in pigs from ZnAA-supplemented sows and those receiving gastric intubation with ZnMet (P=0.05 and P<0.0001, respectively). Post-weaning liver tissue concentrations for Zn (P<0.0001) and Fe (P=0.04) were higher and for Cu lower (P<0.0001) in pigs intubated with ZnMet. Pigs from ZnAA-supplemented compared with control-fed sows tended (P<0.1) to have increased villi height and villus:crypt ratio in the jejunum and higher (P=0.1) goblet cell counts in the ileum. Goblet cell counts of ZnMet-intubated (P=0.03) and LPS-challenged pigs (P=0.05) were also higher in the jejunum. Supplementation of ZnAA to gestating sows increased (P=0.04) E. coli colony forming unit counts in the small intestinal mesenteric lymph nodes of early-weaned pigs. In conclusion, dietary addition of ZnAA to gestating sows and gastric intubation of ZnMet improved Zn status of suckling pigs.

Early social isolation alters behavioral and physiological responses to an endotoxin challenge in piglets

Psychosocial stress in the form of maternal deprivation and social isolation during early postnatal life induces persistent alterations in behavioral and physiological mechanisms of adaptation. One consequence may be an increased susceptibility to diseases in later life. Therefore, the aim of the present study was to investigate in domestic piglets the effects of a repeated social isolation (2 h daily from day 3 to day 11 of age) on behavioral, endocrine and immune responses to an endotoxin challenge with lipopolysaccharide (LPS) 1 day or 45 days after the isolation period. Peripheral LPS administration caused serious sickness behavior (somnolence, shivering, vomiting) and provoked profound increases in circulating tumor necrosis factor-alpha (TNF-alpha), ACTH and cortisol concentrations. The prior social isolation treatment enhanced signs of sickness and impaired suckling behavior. Early isolated piglets responded to LPS by an increase of shivering on day 12 and by increased vomiting on day 56 compared to controls. Further, there were considerable delays and reductions of time isolated piglets spent suckling on day 12. The repeated isolation stressor diminished TNF-alpha increases after LPS, whereas stress hormone levels were not significantly affected by isolation treatment. Finally, stronger relationships between signs of sickness and physiological measures were revealed in early isolated piglets. The duration of somnolence in isolated piglets was related to changes of cortisol and TNF-alpha concentrations, and the highest impact on duration of shivering was found for changes in cortisol and corticosteroid binding globulin levels. The present results suggest a sustained adaptive sensitization of coping with infection by social stress experience during early development in piglets.

Acute feed intake and acute-phase protein responses following a lipopolysaccharide challenge in pigs from two dam lines

This study was conducted to evaluate the response of two dam lines of pigs to acute increases of LPS. Acute-phase proteins were also measured to determine their potential use as biological indicators of the immune response. Thirty-six pigs (initial body weight = 21.3 +/- 0.48 kg) were allotted by dam line (Lines 1 and 2) and sex (castrates and gilts) to one of three LPS dose treatments and penned individually. Treatments were a single i.m. injection of 0 (LPS-0), 25 (LPS-25) or 50 microg LPS/kg body weight (BW) (LPS-50). Acute changes in feed intake were related to a pre-injection baseline intake. Feeders were weighed daily to establish baseline feed intake (average daily feed intake -48 to 0 h prior to injection). The acute feed intake response (AFIR) was computed as the average daily feed intake 0-48 h after injection divided by baseline intake. Serum was harvested at time 0 and 48 h after injection. LPS-0 pigs grew faster and consumed more feed than the LPS-25 or LPS-50 pigs (0.79 kg/d versus 0.51 and 0.50 kg/d; 1.15 kg/d versus 0.96 and 0.89 kg/d, respectively; P<0.001). The AFIR of Line 1 castrates and Line 2 gilts was similar for LPS-25 and LPS-50 treatments, while Line 1 gilts and Line 2 castrates had decreased AFIR with increased LPS dose (sex x line x LPS, P<0.05). Three of 18 castrates died but no gilts died following the LPS challenge (P<0.10). Castrates had higher haptoglobin (Hpt) concentrations than gilts on d 0 (18.1 units of absorption/mg of protein versus 13.1 units of absorption/mg of protein; P<0.03). Line 1 pigs had higher C-reactive protein (CRP) concentrations than Line 2 pigs (P<0.05) on d 0. LPS treatment did not change serum concentrations of CRP, Hpt or ceruloplasmin (Cp). However, the change in serum amyloid A (SAA) concentration decreased quadratically (from 0 to 48 h) with increasing LPS dose (P<0.02). This change in SAA was negatively correlated with the AFIR (r= -0.80; P<0.001). In general, castrates appear to be more sensitive to endotoxin challenges than gilts. Serum amyloid A, but not the other acute-phase proteins evaluated, was a good biological indicator of immune system activation following an acute lipopolysaccharide challenge when compared to the acute change in feed intake.

CNS injury: the role of the cytokine IL-1

Injury to the central nervous system (CNS) and the resulting neuronal loss contribute significantly to morbidity and mortality in human and domestic animal populations. Most insults induce inflammation and the expression of cytokines. The specific roles of these proteins in neurological damage and repair are not completely understood. However, members of the interleukin-1 (IL-1) family have clear therapeutic potential: the IL-1 agonists, IL-1 alpha and IL-1 beta, are induced by CNS injury, and central injection of IL-1 increases, whilst peripheral or central administration of the IL-1 antagonist, IL-1ra, reduces the extent of the damage by more than 50%. The mechanism of action of these cytokines is the subject of intense research. In this review, we summarise approaches that are being used to investigate neuronal cell death, and the contribution of inflammation and cytokines, in particular the IL-1 family, to neurodegenerative disorders.

From hormones to immunity: the physiology of immunology

Discoveries in the physiology of immunology have increased at an increasing rate during the past two decades. It is now recognized that the immune system is just another physiological system that regulates, and is regulated by, other physiological systems such as the brain. These advances make it clear that recent findings in genomic biology must be interpreted in the context of the environment in which animals and humans live. Lack of a strong genetic basis for significant human mental health disorders, such as major depression, points to the critical importance of interactions. Several examples of environmental x genetic x disease interactions are presented. Regulation of cells of the hematopoietic lineage by two genes that control over 80% of postnatal growth, growth hormone and IGF-I, are then highlighted. The reciprocal relationship of how proinflammatory cytokines from the immune system regulate the growth hormone/IGF-I axis is also summarized. Particular emphasis is placed upon TNFalpha-induced IGF-I resistance in neurons, muscle cells and epithelial cells. This cytokine regulation of hormone action may ultimately be more important for human and animal health than direct effects of growth hormone and IGF-I on hematopoietic cells. Wasting of AIDS patients is given as an important clinical example of how TNFalpha from an activated immune system reduces IGF-I sensitivity in multiple physiologic systems, including muscle, nervous and hematopoietic tissues.

Neuroendocrine and immune responses to acute endotoxemia in suckling and weaned piglets

The objective of this study was to characterize effects of weaning stress on behavioural, endocrine and immune responses to acute peripheral lipopolysaccharide (LPS) challenge in neonatal pigs. Weaning in 28-day-old piglets was accompanied by a significant increase in ACTH concentrations (p = 0.0378) and an increase in basal cortisol level (p = 0.0135). There was also a significant suppressive effect on lymphocyte proliferation in response to concanavalin A (p = 0.0048) in newly weaned piglets. Peripheral administration of LPS induced vomiting, diarrhoea and somnolence in both suckling and weaned piglets. The frequency of these signs of sickness was significantly higher in weaned piglets compared with suckling piglets (p = 0.0049). Additionally, LPS significantly increased plasma concentrations of TNF-alpha, cortisol and ACTH. While weaned piglets reacted to LPS with a higher release of ACTH (p = 0.0239) and cortisol (p = 0.0015) than suckling piglets there was no significant effect of weaning on the magnitude of TNF-alpha. The present data indicate that weaning suppresses the lymphocyte function, causes changes in endocrine regulation and has a substantial effect on the behavioural and endocrine response to an acute peripheral LPS challenge; consequently it could increase disease susceptibility.

Effects of prenatal stress on cellular and humoral immune responses in neonatal pigs

In the present study, we investigated the effects of a daily 5 min restraint stress of pregnant sows in the last five gestational weeks on the development and reactivity of the immune system of the offspring. Maternal stress resulted in significant decreased serum immunoglobulin G (IgG) concentrations in suckling piglets at 1 and 3 days of age. Furthermore, the stress treatment of the sows had an immunosuppressive effect on lymphocyte proliferation in response to the T-cell mitogen concanavalin A (ConA) at postnatal days 1 and 7. A suppressive effect was also found in response to the B-cell mitogens lipopolysaccharid (LPS) at days 1 and 35 and pokeweed mitogen (PWM) at day 1 of life, whereas natural killer (NK) cell cytotoxicity was not altered by prenatal stress. The relative thymus weights were significantly reduced in prenatally stressed piglets on the first and 35th day of life and the morbidity and mortality during the suckling period were significantly increased in prenatally stressed litters, as shown by a higher frequency of diseased and died piglets per litter. In addition, the ConA-, LPS- and PWM-stimulated lymphocyte proliferation at the age of 7, 21 and 35 days, and the NK cell cytotoxicity at the age of 21 and 35 days decreased in prenatally stressed and in control piglets 1h after a corticotropin (ACTH) injection. However, the cellular immunity was always higher in the control piglets which might be a result of the weaker stress hormone reactivity in prenatally stressed animals. In conclusion, the results provide first experimental evidence that prenatal maternal stress during late gestation is able to impair both humoral and cellular immune function in suckling piglets. The data also suggest that gestational stress in pigs may affect the ontogeny of the foetal immune system with consequences on the susceptibility to diseases and immune responsiveness to stressful stimuli of the offspring.

Sows intramammarily inoculated with Escherichia coli influence of time of infection, hormone concentrations and leucocyte numbers on development of disease

The aim of this study was to identify factors that influence the development of disease in sows inoculated with Escherichia coli in the mammary gland. Ten cross-bred primiparous sows were intramammarily inoculated with living E. coli bacteria at different time points before parturition: seven sows within 48 h before parturition and three sows approximately 96 h before parturition. Before and after inoculation, blood samples and mammary gland biopsy specimens were collected and clinical observations were made. All seven sows inoculated close to parturition developed a rectal temperature of >39.5 degrees C during the first 48 h post-partum and two of them also showed other signs of clinical disease. In the sows inoculated 4 days before parturition, the rectal temperature never exceeded 39.5 degrees C during the first 48 h post-partum and none of them showed any other sign of clinical discase. There was a tendency (P < 0.1) that histological signs of mastitis were more frequent in the sows inoculated close to parturition. There were no overall differences between the two groups of sows in plasma concentrations of cortisol, oestradiol-17beta and 15-ketodihydro-PGF2alpha before inoculation. Before inoculation, the number of neutrophils in the blood was overall higher (P < 0.05) in the group of sows that were inoculated close to parturition. In comparison, the number of lymphocytes before inoculation had a tendency (P < 0.1) to be lower in that group. The data suggest that the time of infection of the mammary gland relative to parturition and the number of circulating neutrophils at the time of infection influence the development of chinical coliform mastitis in the sow.

Effect of cervical vagotomy on sympathetic nerve responses to peripheral interleukin-1beta

Although the vagus nerve is an important neural pathway mediating immune-to-brain communication, the role of the vagus in mediating sympathetic nerve discharge (SND) responses to peripheral cytokines is not well established. In the present study we determined renal, interscapular brown adipose tissue (IBAT), splenic, and lumbar SND responses before and for 60 min after the intravenous administration of interleukin-1beta (IL-1beta, 100 ng) in chloralose-anesthetized, sham-vagotomized and cervical-vagotomized (bilateral) rats. In sham-vagotomized rats, IL-1beta administration increased (P<0.05) splenic and lumbar SND while renal and IBAT SND remained unchanged from control levels. Renal, splenic, and lumbar SND were increased (P<0.05) whereas IBAT SND remained unchanged from control after IL-1beta in vagotomized rats. Renal, splenic, and lumbar SND responses were significantly higher after IL-1beta in vagotomized compared with sham-vagotomized rats. These results demonstrate that regionally-selective SND (renal, splenic, and lumbar) responses to IL-1beta can occur in the absence of the vagus nerve and suggest that the vagus nerve provides a tonic inhibition to the discharges in these nerves in response to peripheral IL-1beta.

Functional asymmetry of thymus and the immune response in mice

We have studied the capability of the mouse thymus for asymmetrical formation. Concanavalin A (Con A)-stimulated proliferation of thymocytes from the right and left lobes of the thymus appeared to be significantly different. The direction of the differences depends on the dominance of the brain hemispheres with regard to motor asymmetry. In mice with right-dominant hemispheres, thymocytes from the left lobe of the thymus demonstrate a higher level of Con A-stimulated proliferation than those from the right lobe. In mice with left-dominant hemispheres, we found the opposite dependence. The in vivo experiments showed that the properties of cells from the contralateral lobes of the thymus proved to be a deciding factor that defines the differences at the level of the immune response in recipient mice with left-dominant hemispheres. This effect was less pronounced in mice with right-dominant hemispheres. Further analysis showed that left and right-dominant hemisphere mice differ according to the immune response only if mice from both groups received cells from the left but not from the right lobe of the thymus. That is, in the formation of the immune response to sheep red blood cells, the functional asymmetry of both the brain and thymus is of great importance. The experiments show that brain hemispheres and cells from different lobes of the thymus are able to interact in the regulatory effect on the immune response. The injection of cells from the thymus lobe ipsilateral to the dominant hemisphere, results in a significant excess of the immune response in left-dominant hemisphere mice in comparison with the response of right-dominant hemisphere mice. It can be concluded that this work demonstrates, for the first time, the asymmetrical function of a bilateral immune organ--the thymus. The asymmetry is shown not only at the level of Con A-induced proliferative activity but also at the level of the influence on the humoral T-dependent immune response in mice. Besides, we have found the interaction of brain hemispheres and thymus lobes in the regulation of the immune response.

Mapping quantitative trait loci for stress induced alterations in porcine leukocyte numbers and functions

To identify quantitative trait loci (QTLs) with effects on 'stress' induced alterations of porcine immune functions, a number of immune capacity traits were analysed in the F2 generation of a Wild Boar--Yorkshire intercross. All traits were measured prior, and one day after, exposure to experimental 'stress' (mixing and transport). The 'stress' protocol induced a decrease in numbers of circulating neutrophils and in spontaneous proliferation in vitro, whereas phagocytic capacity, mitogen induced proliferation and spontaneous IL-2 activity increased. The IFN-alpha production tended to decrease, although the individual variation was pronounced. More than 200 genetic markers have been scored in the entire pedigree and were used to trace the inheritance of individual chromosome segments. Wild Boar alleles were on average associated with higher mitogen induced IL-2 activity and a slightly lower decrease in IFN-alpha production after mixing and transport. Four QTLs with significant effects were identified; one influencing 'stress' induced alteration in numbers of neutrophils (chromosome 8), one influencing spontaneous proliferation after 'stress' (chromosome 2), one influencing mitogen induced IL-2 activity after 'stress' (chromosome 6) and one influencing 'stress' induced alterations in mitogen induced IL-2 activity (chromosome 12). In addition, several suggestive QTLs were indicated.

Cytokines as markers for infections and their effect on growth performance and well-being in the pig

Exposure to micro-organisms commonly elicit the production of cytokines. These soluble factors enhance several innate immune functions that aim to limit the spread of infection. Further, many of the pro-inflammatory cytokines regulate the ensuing specific immune response. In addition to their effects on cells of the immune system, cytokines also are important regulators in the so called immune-neuroendocrine network. The microbial structures that are necessary for induction of cytokine production are not conclusively determined but in general, bacteria preferentially induce the production of IL-1, TNF-alpha, IL-6, and IL-8, whereas virus induce the production of Type 1 interferons (IFN-alpha/beta). The onset of production of these cytokines is rapid, and several of them may reach systemic levels during a short period after infection. Thus, cytokines can serve as markers for ongoing infections and be used for discrimination between infections of bacterial or viral origin. Results from experimental and field studies show that serum IFN-alpha and IL-6 seem to be useful markers for ongoing (subclinical) viral and bacterial infections, respectively, in the pig. Consequently, demonstration of these cytokines can be valuable tools in heard health monitoring programs.

Interleukin-1beta-converting enzyme-deficient mice resist central but not systemic endotoxin-induced anorexia

Interleukin-1beta (IL-1beta) mediates many of the behavioral responses to infection and inflammation, and IL-1beta-converting enzyme (ICE) processes intracellular IL-1beta, leading to its maturation and secretion. Here we demonstrate that intracerebroventricular injections of lipopolysaccharide (LPS) produced a greater reduction in both food intake and food-motivated behavior in wild-type compared with ICE-deficient (ICE -/-) mice. This defect occurred although ICE -/- mice were able to fully respond to intracerebroventricular injections of IL-1beta. In contrast, ICE -/- mice remained fully responsive to intraperitoneal injections of LPS. These results indicate that brain, but not peripheral, IL-1beta plays a critical role in the depression in food intake that occurs during inflammation.

Effects of social status after mixing on immune, metabolic, and endocrine responses in pigs

The effects of social rank on immune, metabolic, and endocrine responses were studied in 10 newly mixed groups of German Landrace pigs (9 individuals each) at an age of 12 weeks. Immediately after mixing, the agonistic interactions (AI) of all group members were continuously recorded over 3 days (10 h daily). An individual dominance value (DV) was calculated by the number of wins minus defeats in relation to all decisive fights (DV < or = 0, subordinate; DV > 0, dominant). Blood samples were taken 24 h before and 3 days after mixing. The data showed that the social status had a significant effect on lymphocyte proliferation in responses to different mitogens: socially dominant pigs had higher proliferative response than subordinate pigs. In addition, during the observation period the lymphocyte activation by mitogens increased in the dominant animals and decreased in the subordinate animals with increasing number of agonistic interactions. The rise in total serum IgG concentration 3 days after mixing was higher in dominant pigs compared with subordinates. The dominance status did not significantly affect plasma metabolic levels nor cortisol concentrations. However, mixing appeared to increase glucose and total protein values and to decrease alkaline phosphatase and cortisol levels in both, dominant and subordinate pigs. In conclusion, mitogen induced cell proliferation seems to be a valuable marker for acute social stress in pigs.