Induction of circulating tumor necrosis factor cannot be demonstrated during septicemic salmonellosis in calves

Bidirectional communication: Growth and immunity in domestic livestock1,2,3,4

Evidence continues to mount supporting the existence of a bidirectional communication network between the immune system and the somatotropic axis in a variety of species. For more than 4 decades, researchers have sought and identified linkages between the growth axis and the immune system. Although significant advances have been made with regard to elucidation of various bidirectional communication pathways between the immune system and growth axis in humans and rodents, the current paper focuses on the relationships between the immune system and somatotropic axis in sheep, cattle, and swine. Aspects from historical and current research associated with changes in somatotropic function following immune challenges with endotoxin, parasites, viruses, and bacteria have been provided. Collectively, these studies demonstrate that a bidirectional communication network, similar to that described in humans and rodents, also exists in a variety of domestic livestock. Identifying and understanding this bidirectional communication network could have significant economic benefits if it leads to intervention strategies to prevent production losses associated with sickness and disease.

Efficacy of an Escherichia coli J-5 mutant strain bacterin in the protection of calves from endotoxin disease caused by subcutaneous challenge with endotoxins from Escherichia coli

The purpose of this trial was to examine the potential of a new Escherichia (E) coli J-5 mutant strain bacterin to reduce the severity of clinical disease caused by subcutaneous challenge with endotoxins of Gram-negative bacteria in calves. Day-old to 3-day old calves (n = 40 per study phase) were randomly assigned to either of two treatment groups, i.e. a vaccinated or a placebo group. Calves in the vaccinated group received an inactivated bacterin containing a J-5 mutant strain of E. coli via subcutaneous route at 2-4 days of age and at 14 days thereafter. The placebo contained only adjuvant and saline in lieu of the antigen. Lipopolysaccharides (LPS) originating from E. coli were administered subcutaneously 3 weeks after the booster dose. The LPS challenge dosages were 1 and 8 microg/kg in study phases I and II, respectively. Various clinical, physiological, hematological, and serological parameters were measured at specific time intervals after challenge. The data were mostly analysed using peak changes from baseline recorded during the observation period. By the time of challenge the titers in vaccinated calves had increased significantly more than in the unvaccinated controls. Disease severity following subcutaneous challenge was dose dependent. In phase I, placebo calves were only mildly challenged whereas in phase II placebo calves showed a moderate challenge. After a mild challenge, there was little evidence of protection due to vaccination as only attitude was significantly improved in the vaccinates. In contrast, after a moderate challenge rectal temperature, hematocrit, blood glucose concentrations, and leukocyte changes were significantly better in the vaccinated group. In conclusion, the results of this study show that following a subcutaneous endotoxin challenge that induces a moderate clinical response, calves that were previously vaccinated with the E. coli J-5 bacterin were better protected than those in the placebo group.

Cytokines in Salmonellosis

The recruitment and activation of phagocytic cells in infected tissues and the induction of T-cell- and B-cell-dependent acquired immunity are crucial for the control and resolution of Salmonella infections. These complex processes require the interaction of bacteria with a multitude of cell surface receptors and the controlled production of soluble mediators. The mechanisms of cytokine induction in response to Salmonella and the role of cytokine networks in Salmonella infections are the main foci of this review. Pathogen-associated molecular pattern receptors play an important role in recognition of bacteria by the host. Effective immunity against the bacterium therefore relies on the ability of the host to recruit phagocytes in the tissues and to enhance the antibacterial functions of these inflammatory cells. TNF-a, IFN-?, IL12, IL15, and IL18 are needed for the full expression of innate host resistance to Salmonella. The genes for mammalian cytokines can be cloned into suitable vectors and expressed in Salmonella as functional proteins. The in vivo production of cytokines by Salmonella carriers can have therapeutic applications and can modulate immune functions in the host. The possibility to modulate antigen-specific immune responses by expressing cytokines in Salmonella is illustrated by the increase in Salmonella-specific IgA responses induced by administration of IL-5-expressing bacteria. The same cytokines that are responsible for endotoxic shock are elevated in the late stages of lethal Salmonella infections, indicating that the toxicity of Salmonella lipopolysaccharide (LPS) may actually be contributing to the death of the host.

Effects of chlorpromazine, pentoxifylline and dexamethasone on mRNA expression of lipopolysaccharide-induced inflammatory cytokines in bovine peripheral blood mononuclear cells

The effects of chlorpromazine (CPZ), pentoxifylline (PTX) and dexamethasone (DEX) on mRNA expression of lipopolysaccharide (LPS)-induced proinflammatory cytokines were examined in bovine peripheral blood mononuclear cells (PBMCs) in vitro. The expression of inflammatory cytokine mRNAs was analyzed by RT-PCR and Southern blot hybridization in bovine PBMCs. CPZ and DEX decreased the expression of cytokine mRNA (such as interleukin-1 beta and tumor necrosis factor-alpha) after stimulation with LPS in a dose-dependent manner. However, pretreatment with PTX had no inhibitory effect on the mRNA expression of proinflammatory cytokines. These results indicated that pretreatment with CPZ and DEX might be effective to reduce the production of LPS-induced inflammatory cytokines in bovine PBMCs in vitro.

Development of a clinical syndrome resembling haemorrhagic septicaemia in the buffalo following intravenous inoculation of Pasteurella multocida serotype B:2 endotoxin and the role of tumour necrosis factor-alpha

Clinical changes and acute phase responses, including tumour necrosis factor-alpha (tnfalpha), in six buffalo calves were examined following intravenous inoculation of a bolus of endotoxin (1 microg kg(-1) bodyweight in 10 ml of phosphate-buffered saline [ pbs ]) extracted from Pasteurella multocida serotype B:2, the bacterium responsible for haemorrhagic septicaemia (hs) in Asia. Endotoxin injection caused a rapid onset of clinical signs characterised by dullness, sternal recumbency, elevated rectal temperatures, excessive salivation and dyspnoea that lasted for up to 12 hours post-inoculation (p.i.). Serum concentrations of tnfalpha rose within 1 hour p.i. to reach peak values ranging between 8 and 140 ng ml(-1) at 1-2 hours p.i. and then declined rapidly to baseline levels 3-5 hours p.i. Endotoxin injection induced other acute phase changes, including a rapid leucopenia and reductions in the serum concentrations of iron and zinc and a delayed but prolonged increase in haptoglobin from 12 hours p.i. that reached a plateau from about 60 hours p.i. Three control calves injected with 10 ml pbs showed no clinical or blood compositional changes. By reproducing key signs of hs the work confirms a pivotal role of endotoxin in the pathogenesis of hs and emphasises the exquisite sensitivity of the buffalo to P multocida endotoxin.

Morphologic and molecular characterization of Salmonella typhimurium infection in neonatal calves

The host response to Salmonella plays a major role in the outcome of infection. The present study was undertaken to further characterize Salmonella typhimurium infection in neonatal calves at both the morphologic and the molecular level using the ligated ileal loop model. Eight 4-5-week-old male Holstein calves underwent laparotomy, and loops were prepared in the ileum. The loops were either inoculated with an S. typhimurium strain pathogenic for cattle or injected with sterile LB broth as control. Samples for histology, transmission and scanning electron microscopy, and RNA extraction were collected at various time points between 5 minutes and 12 hours postinfection. Invasion of both M cells and enterocytes began at 15 minutes postinfection. No specific cell type was the main target for invasion. Intracellular bacteria were observed in the lamina propria after 1 hour postinfection. A severe acute neutrophilic response was associated with invasion of the Peyer's patches. Upregulated expression of CXC chemokines (interleukin [IL]-8, growth-related oncogenes, [GRO] alpha and gamma, and granulocyte chemotactic protein [GCP]2) was detected by reverse transcription polymerase chain reaction beginning at 1 hour postinfection. Expression of proinflammatory (IL-1beta, IL-18, and tumor necrosis factor [TNF]alpha) and anti-inflammatory (IL-10, IL-IRa, and IL-4) cytokines was also assessed. A marked increase in expression of IL-1beta was observed, whereas the profile of expression of IL-18 and TNFalpha did not change after infection. Upregulation of IL-1Ra and IL-4 but not of IL-10 was observed. These findings indicate that infection of bovine ligated ileal loops with S. typhimurium results in an acute neutrophilic inflammatory response that is associated with the upregulation of CXC chemokines (IL-8, GROalpha and gamma, and GCP2), IL-1beta, IL-IRa, and IL-4.

Bacterial virulence, proinflammatory cytokines and host immunity: how to choose the appropriate Salmonella vaccine strain?

Salmonella infection in its mammalian host can be dissected into two main components. The co-ordinate expression of bacterial virulence genes which are designed to evade, subvert or circumvent the host response on the one hand, and the host defence mechanisms which are designed to restrict bacterial survival and replication on the other hand. The outcome of infection is determined by the one which succeeds in disturbing this equilibrium more efficiently. This delicate balance between Salmonella virulence and host immunity/inflammation has important implications for vaccine development or therapeutic intervention. Novel Salmonella vaccine candidates and live carriers for heterologous antigens are attenuated strains with defined genetic modifications of metabolic or virulence functions. Although genetic defects of different gene loci can lead to similar degrees of attenuation, effects on the course of infection may vary, thereby altering the quality of the elicited immune response. Studies with gene-deficient animals indicate that Salmonella typhimurium strains with mutations in aroA, phoP/phoQ or ssrA/ssrB invoke different immune responses and that a differential repertoire of pro-inflammatory cytokines is required for clearance. Consequently, Salmonella mutants defective in distinct virulence functions offer the potential to specifically modulate the immune response for defined medical applications.

Receptors for insulin-like growth factor-I and tumor necrosis factor-alpha are hormonally regulated in bovine granulosa and thecal cells

Mastitis induces release of tumor necrosis factor-alpha (TNFalpha) and has been linked with reduced reproductive performance. To further elucidate the role and mechanism of action of TNFalpha on ovarian cells, the effect of TNFalpha on insulin-like growth factor-I (IGF-I)-induced steroidogenesis and IGF-I binding sites in granulosa and thecal cells as well as the hormonal regulation of TNFalpha receptors were evaluated. Granulosa and thecal cells were obtained from small (1-5mm) and large (> or =8mm) bovine ovarian follicles, respectively, and cultured for 3-4 days. During the last 2 days of culture, cells were treated with various hormones and steroid production and specific binding of 125I-IGF-I and 125I-TNFalpha was determined. Two-day treatment with 30 ng/ml of TNFalpha decreased (P<0.05) IGF-I-induced estradiol production by granulosa cells and IGF-I-induced androstenedione production by thecal cells. Two-day treatment with 10 and 30ng/ml of TNFalpha decreased (P<0.05) specific binding of 125I-IGF-I to thecal cells, but had no effect on specific binding of 125I-IGF-I to granulosa cells, or on specific binding of 125I-IGF-II to thecal cells. TNFalpha did not compete for 125I-IGF-I binding to granulosa or thecal cells whereas unlabeled IGF-I suppressed 125I-IGF-I binding. Insulin inhibited (P<0.10) whereas FSH had no effect on the number of specific 125I-TNFalpha binding sites in granulosa cells. In contrast, LH increased (P<0.10) whereas insulin had no effect on specific 125I-TNFalpha binding sites in thecal cells. These results suggest that IGF-I and TNFalpha receptors in granulosa and thecal cells are regulated by hormones differentially.

Role of endotoxin in the pathogenesis of haemorrhagic septicaemia in the buffalo

The pathogenesis of haemorrhagic septicaemia in buffalo infected with Pasteurella multocida is poorly understood. However, the characteristic of sudden onset leading to the rapid death of infected animals is similar to that seen in other clinical conditions known to involve endotoxic shock. The objectives of the work were to assess the contribution of endotoxaemia to the disease's pathogenesis and to characterize the pathophysiological reaction, including the acute phase response, of buffalo to experimental infection with P. multocida serotype B:2, the bacterium responsible for the disease in Asia. After intranasal infection of eight buffaloes with a culture of a field isolate of P. multocida serotype B:2, three animals succumbed to the disease at 26-30 h post-infection (p.i.) and five survived. Rectal temperatures of infected animals rose to a peak at about 10 h p.i. and surviving animals showed a second peak in rectal temperature at 36 h p.i. Endotoxin was present only in serum of non-surviving animals 3-5 h before death or killing during which time concentrations increased rapidly, correlating with the development of overt clinical signs and reductions in rectal temperature, concentrations of white blood cells, serum thyroxine, iron, copper and zinc, an increase in serum haptoglobin and cortisol and the detection of a low-grade bacteraemia. A strong acute phase response was maintained in surviving animals with a progressive rise in serum haptoglobin over 96 h p.ia slow rise in the serum copper concentration from 24 h p.i. and an increase, from about 65 h p.iin serum alpha(1)-acid glycoprotein. The findings demonstrate that a progressive endotoxaemia and associated sequelae correlates with the development of overt haemorrhagic septicaemia disease and sudden death in buffalo.

Acute phase response in dairy cows with experimentally induced Escherichia coli mastitis

Six Finnish Ayrshire cows were challenged intramammarily with 1500 CFU of Escherichia coli (E. coli) into single udder quarters, and the challenge was repeated into contralateral quarters 3 weeks later. All cows received flunixine meglumine once, and 3 of them were also treated with enrofloxacin. At the 2nd challenge, treatments were changed vice versa. The development of mastitis was followed by monitoring of systemic and local clinical signs, and with serial milk and serum samples. Intramammary challenge with E. coli produced clinical mastitis in all cows, the severity of the disease varying greatly between the animals. No significant changes between the 2 treatment regimens or sequent challenges were found for any of the clinical parameters. The response of each cow followed the same pattern after both challenges; three of the cows became mildly and the other 3 either moderately or severely affected. Two severely affected cows had to be euthanized because of severe mastitis. Serum haptoglobin and amyloid-A concentrations peaked 2-3 days after bacterial challenge. Serum haptoglobin did not correlate with the severity of the disease. Serum amyloid-A rose gradually in the severely affected cows, and significant differences were found between severely versus moderately or mildly affected cows at day 4. Serum tumor necrosis factor alpha concentrations increased only in the severely affected cows. Serum cortisol response was prolonged in the severely diseased animals, and was significantly lower after the second challenge. Serum nitrite/nitrate concentration increased in the severely affected cows. This indicated excess nitric oxide production during acute E. coli mastitis. Strongly decreased milk production, and high bacterial growth in the infected quarters were best predictors for the outcome from acute E. coli mastitis.

Host cytokine response and resistance to Salmonella infection

Knowledge of the host response, of the resistance process, and of the mediators committed against Salmonella infection is essential to progress towards better means of prophylaxis and eradication. In this context, the present contribution attempts to interconnect, with the pivotal role of the macrophage, the early resistance process under the control of the Nramp1 gene and the cytokine response for resolving infection. IL-12 produced by macrophages is an inducer of IFN-gamma production, which in turn activates the macrophage antibacterial activity and synergizes its effects with TNF-alpha. All three of these cytokines are powerful actors in the first line of anti-Salmonella defence. It can be pointed out that susceptible and resistant individuals do not seem to see the cytokine environment the same way, the former being unresponsive to IL-1 or GM-CSF treatment and deficient in IFN-gamma production. These discrepancies may rely on cell signalling events that could be defective in macrophages of the susceptible phenotype.

Acute phase response in dairy cows with experimentally induced Escherichia coli mastitis

Six Finnish Ayrshire cows were challenged intramammarily with 1500 CFU of Escherichia coli (E. coli) into single udder quarters, and the challenge was repeated into contralateral quarters 3 weeks later. All cows received flunixine meglumine once, and 3 of them were also treated with enrofloxacin. At the 2nd challenge, treatments were changed vice versa. The development of mastitis was followed by monitoring of systemic and local clinical signs, and with serial milk and serum samples. Intramammary challenge with E. coli produced clinical mastitis in all cows, the severity of the disease varying greatly between the animals. No significant changes between the 2 treatment regimens or sequent challenges were found for any of the clinical parameters. The response of each cow followed the same pattern after both challenges; three of the cows became mildly and the other 3 either moderately or severely affected. Two severely affected cows had to be euthanized because of severe mastitis. Serum haptoglobin and amyloid-A concentrations peaked 2-3 days after bacterial challenge. Serum haptoglobin did not correlate with the severity of the disease. Serum amyloid-A rose gradually in the severely affected cows, and significant differences were found between severely versus moderately or mildly affected cows at day 4. Serum tumor necrosis factor alpha concentrations increased only in the severely affected cows. Serum cortisol response was prolonged in the severely diseased animals, and was significantly lower after the second challenge. Serum nitrite/nitrate concentration increased in the severely affected cows. This indicated excess nitric oxide production during acute E. coli mastitis. Strongly decreased milk production, and high bacterial growth in the infected quarters were best predictors for the outcome from acute E. coli mastitis.

Inhibitory effect on LPS-induced tumor necrosis factor in calves treated with chlorpromazine or pentoxifylline

The inhibitory effect of chlorpromazine (CPZ), pentoxifylline (PTX) and dexamethasone (DEX) was investigated in a model of endotoxin shock in Holstein calves following an intravenous administration of Esherichia coli endotoxin (LPS). Initial correlations with its effects on the levels of tumor necrosis factor (TNF), a pivotal mediator of endotoxin shock, and clinical signs were obtained. The pretreatment of CPZ or DEX significantly decreased the serum levels of TNF, and reduced endotoxic shock. But the pretreatment of PTX hardly reduced the increase of serum TNF levels and endotoxin shock. The levels of serum endotoxin were not significantly different a minute of postinjection of LPS in calves. The results of this study indicate that pretreatment of CPZ or DEX inhibit various biological effects on endotoxin in calves.

Plasma cytokines in paediatric typhoidal salmonellosis: correlation with clinical course and outcome

We evaluated the clinical profile, outcome and serial plasma interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) concentrations in 38 consecutive children (aged 6 months-14 years) admitted with culture-proven multidrug-resistant typhoid. All children received therapy for 14 days with either i.v. ceftriaxone or oral cefixime, with comparable outcome. Concentrations of IL-6 and TNF-alpha were significantly elevated in over 50% of the cases and correlated with clinical severity of illness as quantitated by the typhoid morbidity score. Sequential measurements revealed a significant decrease in IL-6 and TNF-alpha concentrations within 7 days of initiation of therapy (P<0.05). While no clear relationship was seen with time-to-defervescence, the failure rate was significantly higher in children with baseline serum IL-6 values >400 pg/ml (P<0.05). Our data suggest that plasma cytokine activity is frequently elevated in children with typhoidal salmonellosis, and IL-6 concentrations show a correlation with clinical severity and recovery from the illness.

Elevated levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) activities in the sera and milk of cows with naturally occurring coliform mastitis

The presence of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) activities was determined in milk and serum of cows with naturally occurring coliform mastitis (CFM). TNF-alpha was detected in the sera from 26 of 32 cows with CFM. TNF-alpha levels were higher in the sera than in the milk. IL-6 was high in the sera of surviving CFM animals, but was low in animals that died and in healthy controls. Furthermore, the mean level of IL-6 was 20-fold higher in the milk than in the sera of mastitic cows. The level of IL-6 in the serum was correlated to that in the milk in individual animals. The presence of IL-6 and TNF-alpha in the sera appears to relate to severe clinical condition of CFM, in the milk whereas they may play a role in generating inflammation of the mammary gland.

Regulation of bovine acute phase responses by recombinant interleukin-1 beta

The acute phase response is a collection of physiologic changes initiated early in the inflammatory process. This response is comprised of both localized changes at the site of infection or injury and the initiation of systemic responses, such as the increase in production of acute phase proteins. Cytokines such as interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF) play key roles in the regulation of acute phase response in the species studied to date. To better characterize the acute phase response of cattle, recombinant bovine (rBo). IL-1 beta was administered to cattle. A single administration of rBoIL-1 beta was able to induce a dose dependent increase in body temperature, circulating leukocytes, and serum haptoglobin and fibrinogen concentrations, as well as a decrease in plasma zinc concentration. Five daily administrations of rBoIL-1 beta resulted in heightened and prolonged elevations of haptoglobin and fibrinogen. In addition, alpha 1-acid glycoprotein levels were increased, a response not seen after a single administration of rBoIL-1 beta. These results indicate that IL-1 is an important regulator of the acute phase response in cattle.

Immediate responses in serum TNF alpha and acute phase protein concentrations to infection with Pasteurella haemolytica A1 in calves

The concentrations of tumour necrosis factor-alpha (TNF alpha), serum amyloid A (SAA) and haptoglobin were determined in serum samples taken from four calves in the 10 hours after their intra-tracheal inoculation with Pasteurella haemolytica serotype A1. The concentration of haptoglobin did not increase but the concentration of SAA rose progressively from within two hours of inoculation. The concentration of TNF alpha reached a peak in all the animals two hours after inoculation but had returned to undetectable levels after a further four hours. TNF alpha is likely to be an important mediator of the acute phase response in cattle and SAA is a more rapid bovine acute phase protein than haptoglobin in its response to infection with P haemolytica.

Tumour necrosis factor production by monocytes from cattle infected with Trypanosoma (Duttonella) vivax and Trypanosoma (Nannomonas) congolense: possible association with severity of anaemia associated with the disease

Plasma of cattle infected with Trypanosoma vivax IL2337 was analysed for the presence of bovine tumour necrosis factor (TNF) by EIA in which TNF was captured by a monoclonal antibody (MoAb BC9) and detected by a rabbit polyclonal antiserum. At week 2-3 post infection (p.i.) only a low activity was detected. Therefore, an alternative approach was used in which TNF production was measured ex vivo. Monocytes from T. vivax IL2337-infected cattle manifested a strong TNF production which peaked around week 2 1/2 p.i. Monocytes from pre-infection controls did not produce significant concentrations of TNF. In contrast to the strong production of TNF by monocytes from cattle infected with T. vivax IL2337, TNF production was not detected from monocytes of cattle infected with Trypanosoma congolense ILNat 3.1. Trypanosomiasis due to these parasites differs in the degree if anaemia as indicated by packed cell volume (PCV). T. vivax IL2337 causes a severe, acute PCV fall whereas T. congolense ILNat 3.1. causes a more gradual fall in PCV.

Inhibition of lipopolysaccharide-associated endotoxin activities in vitro and in vivo by the human anti-lipid A monoclonal antibody SdJ5-1.17.15

The present study evaluated the effect of a novel anti-lipid A monoclonal antibody, termed SdJ5, on the in vitro production of tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta by endotoxin- or lipopolysaccharide (LPS)-challenged human peripheral blood mononuclear cells (hPBMC). In addition, the present study determined whether SdJ5 could neutralize the in vivo toxicity of LPS. SdJ5, at a concentration equal to or greater than 3 micrograms/ml, specifically inhibited TNF-alpha and interleukin-1 beta production by hPBMC stimulated with every type of LPS and lipid A assessed. SdJ5 also showed a significantly greater inhibition of cytokine production than a nonrelevant human immunoglobulin M myeloma control. The SdJ5-mediated inhibition of TNF-alpha production was rapid, as the simultaneous addition of the SdJ5 and LPS still resulted in a marked decrease in hPBMC cytokine synthesis. The ability of SdJ5 to neutralize in vivo toxicity was also determined by using LPS from four different strains of gram-negative bacteria. LPS, when preincubated with SdJ5, resulted in a significant decrease in the 24-h mortality rate compared with that for the control. These studies show that the anti-lipid A monoclonal antibody SdJ5 can modulate LPS-induced cytokine production in vitro and increase the survival rate of rats challenged with lethal doses of LPS.

Synthesis of tumour necrosis factor-alpha and interferons by mononuclear cells from Theileria annulata-infected cattle

Bovine macrophage-derived tumour necrosis factor-alpha/cachectin (TNF-alpha) was synthesized when peripheral blood mononuclear cells (PBMC) and purified adherent PBMC from naive and Theileria annulata-infected cattle were incubated in vitro with concanavalin A (Con-A) or bovine recombinant interferon gamma (Bo rIFN-gamma). TNF-alpha production was also induced when adherent PBMC were cultured with T. annulata macroschizont-infected cells. In contrast, non-adherent PBMC from sublethally infected cattle produced interferon (IFN) when incubated with Hu rIL-2, Con-A, phytohaemagglutinin (PHA) or T. annulata macroschizont-infected cells growing as cell lines in vitro. Whilst PBMC from lethally infected cattle spontaneously produced IFN-gamma during advanced stages of infection, the sera of such animals contained type 1 IFN (alpha/beta). IFN was also produced by T. annulata macroschizont-infected cell lines maintained in vitro. This work suggests that cytokines serve as crucial links between proliferating Theileira-infected cells and the characteristic clinical symptoms of tropical theileriosis.

Serum levels of tumor necrosis factor-alpha in calves experimentally infected with Pasteurella haemolytica A1

The purpose of this study was to document the levels of tumor necrosis factor-alpha (TNF) in serum of calves experimentally infected intratracheally with Pasteurella haemolytica A1 and to determine if elevated TNF levels correlate with development of pneumonic pasteurellosis in the bovine. Serum samples were collected at sequential time periods from 0 h to 72 h post inoculation with P. haemolytica. TNF levels in those sera were measured by a cytotoxicity assay utilizing the TNF-sensitive WEHI 164 mouse fibrosarcoma cell line. Serum TNF levels in infected cattle began to rise at 2 h post inoculation, peaked at approximately 8 h, and decreased to near control levels by 72 h. There was extreme variability in serum TNF among the inoculated animals with levels varying from 120 pg ml-1 to 5000 pg ml-1 at 8 h post inoculation. These levels did not correspond with the degree of lung involvement. All inoculated calves developed lesions of pneumonic pasteurellosis characterized by fibrinous pleuritis with necrotizing, hemorrhagic pneumonia. These results suggest that TNF is probably a significant inflammatory mediator involved in the pathogenesis of bovine pneumonic pasteurellosis.

Fever and acute phase response induced in dwarf goats by endotoxin and bovine and human recombinant tumour necrosis factor alpha

Tumour necrosis factor (TNF), a polypeptide produced by mononuclear phagocytes, has been implicated as an important mediator of inflammatory processes and of clinical manifestations in acute infectious diseases. To study further the potential role of TNF in infectious diseases, recombinant Escherichia coli (E. coli) derived human (r.HuTNF-alpha) and bovine TNF (r.BoTNF-alpha) were intravenously (i.v.) administered in dwarf goats. Rectal temperature, heart rate, rumen motility, plasma zinc and iron concentrations, and certain other blood biochemical and haematological values were studied and compared with the changes seen after E. coli endotoxin (LPS) was administered (dose: 0.1 microgram/kg i.v.). Following a single injection of 4 micrograms/kg of r.BoTNF-alpha, shivering and biphasic febrile response were observed, accompanied by tachycardia, inhibition of rumen contractions, drop in plasma zinc and iron concentrations, lymphopenia, and neutropenia followed by neutrophilia. The i.v. administration of a single injection of 4 micrograms/kg r.HuTNF-alpha induced shivering and biphasic febrile responses, accompanied by anorexia and a similar drop in plasma trace metal concentrations when compared with r.BoTNF-alpha-treated goats. The TNF-alpha-induced symptoms were essentially the same as those that occurred after LPS administration. However, the time of onset of these changes after the injection of TNF-alpha was significantly shorter than after LPS. Moreover, the r.BoTNF-alpha induced a longer lasting neutrophilic leucopenia, less neutrophilia, and a more persistent lymphopenia than after LPS injection. Neither r.BoTNF-alpha nor LPS caused severe haemo-concentration. Furthermore, no cross-tolerance between r.BoTNF-alpha and LPS could be demonstrated. We conclude that both r.BoTNF-alpha and r.HuTNF-alpha induce many of the physiologic, haematologic and metabolic changes that characterize the acute phase response to LPS. The overlapping biological activities of r.BoTNF-alpha, r.HuTNF-alpha and LPS in dwarf goats may indicate that both recombinant tumour necrosis factors have some homology with caprine TNF-alpha.

Effect of interferon-gamma on the production of tumor necrosis factor during acute Escherichia coli mastitis

The effects of recombinant interferon-gamma on the production of tumor necrosis factor in 10 dairy cows with Escherichia coli mastitis were determined. Prophylactic administration of recombinant interferon-gamma prior to the experimental E. coli challenge was effective in modifying the production of endogenous tumor necrosis factor during acute stages of disease. Elevated tumor necrosis factor concentrations were especially evident in cows that developed severe clinical symptoms and eventually died from endotoxemia. These results indicate that both milk and sera tumor necrosis factor concentrations are associated closely with the manifestation of peracute signs of coliform mastitis and are important factors contributing to morbidity and mortality of endotoxic shock. Pretreatment of cows with recombinant interferon-gamma possibly may down-regulate the generation of this potent endogenous inflammatory mediator within infected quarters. Controlling severe inflammation with recombinant interferon-gamma may prevent the tremendous loss in milk production and death that often accompany acute coliform mastitis during the periparturient period.

Serum TNF alpha inhibitor in mouse typhoid

Administration of anti-TNF alpha antiserum enhanced a sublethal infection with salmonellae of moderate virulence (Salmonella typhimurium M525) in innately susceptible (Ity(s)) BALB/c mice, indicating that TNF alpha is important in the early response which suppresses bacterial growth in the reticuloendothelial system (RES). However, only transient low levels of TNF alpha were detectable on day 3 in sera from some, but not all, sublethally infected mice. Conversely, on day 4 of the same infection, clear TNF alpha inhibitory activity was detected in some sera. Neither TNF alpha or any inhibitory activity were detected in sera of lethally infected BALB/c mice undergoing an acute, overwhelming Salmonella infection. In contrast, TNF alpha inhibitory activity, but not TNF alpha, was detected in sera of mice showing a cachectic syndrome induced by persistent high bacterial numbers following intravenous inoculation of a very high dose (2 x 10(7)) of the attenuated aro- S. typhimurium SL3261 strain.

Release of tumor necrosis factor-alpha from bovine alveolar macrophages stimulated with bovine respiratory viruses and bacterial endotoxins

The release of tumor necrosis factor-alpha (TNF-alpha) from cultured bovine alveolar macrophages (BAM) was evaluated following stimulation of BAM with bovine herpesvirus-1 (BHV-1), parainfluenza-3 (PI-3) virus, bovine respiratory syncytial virus (BRSV), Escherichia coli 0111:B4 endotoxin, Pasteurella haemolytica type 1 endotoxin, Pasteurella multocida endotoxin, and virus/endotoxin combinations. A cytotoxic assay system using Georgia bovine kidney cells as targets was used to measure TNF-alpha activity. The cytotoxic activity was neutralized by an anti-human TNF-alpha monoclonal antibody. Stimulation of BAM with 1 median tissue culture infectious dose (TCID50) of live or ultraviolet (UV)-inactivated PI-3 virus/cell resulted in release of TNF-alpha in significantly (P less than 0.05) higher amounts than sham-induced BAM. The quantities of TNF-alpha released after live or UV-inactivated BHV-1 or BRSV induction were not significantly higher than sham-induced BAM. E. coli 0111:B4, P. haemolytica type 1 and P. multocida endotoxins stimulated TNF-alpha release in a dose-dependent manner. Sequential exposure of BAM to 1 TCID50 per cell of either live BHV-1, PI-3 virus or BRSV and then 5 micrograms ml-1 of either E. coli 0111:B4, P. haemolytica type 1 or P. multocida endotoxin caused a significant (P less than 0.05) reduction in detectable TNF-alpha in seven of nine virus/endotoxin combinations tested, when compared with 5 micrograms ml-1 of endotoxin alone. Parainfluenza-3 virus/endotoxin combinations stimulated higher TNF-alpha release when compared with other virus/endotoxin combinations. Five out of six test animals had serum-neutralizing antibodies to PI-3 virus, one out of six had serum-neutralizing antibodies to BHV-1, and two out of six had serum-neutralizing antibodies to BRSV, suggesting a possible relationship between serum neutralizing antibodies and TNF-alpha release from in vitro cultivated BAM.

Treatment with recombinant human tumor necrosis factor-alpha protects rats against the lethality, hypotension, and hypothermia of gram-negative sepsis

Tumor necrosis factor (TNF) is a peptide secreted by macrophages in response to endotoxin that can produce many of the changes seen in septic shock. After cecal ligation and puncture (CLP) rats gradually develop tachycardia, hypotension, tachypnea, and hypothermia. At 5 h post-CLP, rats have a peak in serum levels of endotoxin and 60% of rats have blood cultures that grow Gram-negative rods (Escherichia coli and Klebsiella pneumonia). At 20 h post-CLP all rats develop positive blood cultures. Serum levels of TNF are not reproducibly measurable in rats following CLP. Rats undergoing CLP have a 50-80% mortality with deaths usually occurring 24-72 h postinjury. Repetitive (twice daily x 6 d) i.p. injection of sublethal doses of recombinant human TNF-alpha (100 micrograms/kg) to rats undergoing CLP 1 d after the treatment period resulted in a significant reduction in mortality compared to control rats previously unexposed to rTNF (P less than 0.03). Animals treated with rTNF had no hypotension or hypothermia after CLP and regained normal food intake faster than control rats. 12 h after CLP the gene expression for manganous superoxide dismutase (MnSOD), an inducible mitochondrial metalloenzyme responsible for cellular resistance to injury from toxic reactive oxygen species, was higher in livers of rats treated with rTNF suggesting that the TNF treatment augmented expression of this protective enzyme. Unlike MnSOD, expression of the gene for copper-zinc SOD was not affected by CLP or rTNF treatment. The results suggest that prior treatment with recombinant TNF can ameliorate the lethality, hypotension, hypothermia, and anorexia of Gram-negative sepsis in rats and that the mechanism may be related to enhanced hepatic expression of the gene for MnSOD. Repeated administration of recombinant TNF may be a strategy to minimize mortality and morbidity of Gram-negative sepsis.

Serum TNF alpha in mouse typhoid and enhancement of a Salmonella infection by anti-TNF alpha antibodies

Tumour necrosis factor alpha (TNF alpha) was detected by the L929 cell assay in the sera of mice 1 h after large i.v. inocula of virulent Salmonella typhimurium C5. TNF alpha was not detectable in sera from innately susceptible BALB/c mice during the course of a lethal infection commencing from a low inoculum, or from resistant A/J mice during the course of a lethal or sublethal infection, but only 1 h after i.v. challenge with large numbers of organisms. Administration of a single dose of rabbit polyclonal anti-TNF alpha antiserum on day 1 had no effect on the early course of a lethal infection in A/J mice. However, the same treatment exacerbated a sublethal infection in A/J mice. Anti-TNF alpha treatment did not accelerate the early bacterial net growth rate in the RES. Instead, the cfu count in treated mice continued to increase past the point at which the host response suppressed a further increase in bacterial numbers (the plateau phase) in normal controls. A second dose of anti-TNF alpha antiserum on day 4 together with a higher but still sublethal challenge caused a lethal infection in A/J mice. The results indicate that TNF alpha is important in mediating the plateau phase in a salmonella infection, and its effect may be local.

Bacteraemia in man and animals: an overview

Bacteraemia signifies invasion of the bloodstream by bacteria. In most systemic infections in man and animals, bacteria enter the blood at some stage during the infection and are rapidly distributed throughout the body. A wide variety of organisms have been associated with bacteraemia. Prompt detection of the aetiological agents of bacteraemia is of prime importance in clinical microbiology. There are no defined recommendations for blood cultures in animals but both conventional and improved methods are available for detection of bacteraemia in man. The consequences of bacteraemia are as diverse as the potential aetiological agents. Monoclonal antibodies to the core glycolipid (lipid A) seems very promising for the treatment of bacteraemia and septic shock caused by Gram-negative bacteria in man and animals.

Administration of bacterial lipopolysaccharide elicits circulating tumor necrosis factor-alpha in neonatal calves

The presence of tumor necrosis factor-alpha (TNF-alpha) during endotoxemia in ruminants has not been reported previously. In this study, we detected the in vivo release of bovine TNF-alpha by using WEHI-164 murine fibrosarcoma cells as targets in an 18-h cytotoxicity assay. Treatment of the WEHI-164 cells with 1 microgram of actinomycin D (dactinomycin) enhanced approximately twofold the susceptibility of the cells to TNF-alpha activity. TNF-alpha activity in sera from neonatal calves injected intravenously with 2.7 micrograms of Escherichia coli lipopolysaccharide (LPS) increased rapidly within the first 2 h postinjection and then declined until it was undetectable by 4 h postinjection. Sera taken before LPS administration had no TNF-alpha activity. LPS (10 micrograms/ml) and fetal, newborn, and pooled adult bovine sera alone and in combination had no direct cytotoxic effects on WEHI-164 cells. TNF-alpha cytotoxic activity is probably not due to the presence of interleukin-1 (IL-1), alpha interferon, or gamma interferon in the sera since recombinant human IL-1, natural bovine IL-1, and recombinant bovine alpha and gamma interferons had no direct cytotoxic effects on WEHI-164 cells. A monoclonal antibody that neutralizes recombinant human TNF-alpha significantly reduced the cytotoxic activity of sera from LPS-injected calves.