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

Comparative therapeutic effect of steroidal and non-steroidal anti-inflammatory drugs on pro-inflammatory cytokine production in water buffalo calves (Bubalus bubalis) naturally infected with bronchopneumonia: a randomized clinical trial

In the current study, we compared the therapeutic effects of a non-steroidal and a steroidal anti-inflammatory drug on the production of pro-inflammatory cytokines, interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-12p40 (IL-12p40), interferon gamma (IFNγ), and tumor necrosis factor alpha (TNF-α) in the blood of water buffalo (Bubalus bubalis) calves naturally infected by bronchopneumonia. Twenty-seven buffalo calves (7 ± 2-month-old, 163 ± 12 kg) reared in smallholder farms in El-Dakahlia province in Egypt were identified to have bronchopneumonia and randomly allocated into three equal groups. Ten clinically healthy buffalo calves with negative bronchoalveolar lavage results were served as negative control. Diseased calves were treated with tulathromycin alone, a combination of tulathromycin with dexamethasone (steroidal anti-inflammatory drug) or tulathromycin with flunixin meglumine (non-steroidal anti-inflammatory drug). The results revealed significant elevations (P < 0.05) in the production of selected cytokines in all diseased calves in comparison with healthy animals. Six days post-treatment, a significant inhibition (P < 0.05) in the production of all assessed cytokines was observed in the blood of all treated calves. Interestingly, the serum concentrations of IL-1β and IL-12p40 were returned to the normal levels in pneumonic calves treated with the combination therapy of tulathromycin and flunixin meglumine. A strong significant positive correlation (P < 0.05) was detected between clinical sum scoring and IL-12p40 and TNF-α concentrations. The obtained results indicate the selectively potent anti-inflammatory effect of flunixin meglumine on the production of pro-inflammatory cytokines in pneumonic buffalo calves and highlight the efficacy of flunixin meglumine in the treatment of bronchopneumonia in buffalo calves when used in combination with tulathromycin.

Methods for Optimizing CRISPR-Cas9 Genome Editing Specificity

Advances in the development of delivery, repair, and specificity strategies for the CRISPR-Cas9 genome engineering toolbox are helping researchers understand gene function with unprecedented precision and sensitivity. CRISPR-Cas9 also holds enormous therapeutic potential for the treatment of genetic disorders by directly correcting disease-causing mutations. Although the Cas9 protein has been shown to bind and cleave DNA at off-target sites, the field of Cas9 specificity is rapidly progressing, with marked improvements in guide RNA selection, protein and guide engineering, novel enzymes, and off-target detection methods. We review important challenges and breakthroughs in the field as a comprehensive practical guide to interested users of genome editing technologies, highlighting key tools and strategies for optimizing specificity. The genome editing community should now strive to standardize such methods for measuring and reporting off-target activity, while keeping in mind that the goal for specificity should be continued improvement and vigilance.

Failure of respiratory defenses in the pathogenesis of bacterial pneumonia of cattle

The respiratory system is well defended against inhaled bacteria by a dynamic system of interacting layers, including mucociliary clearance, host defense factors including antimicrobial peptides in the epithelial lining fluid, proinflammatory responses of the respiratory epithelium, resident alveolar macrophages, and recruited neutrophils and monocytes. Nevertheless, these manifold defenses are susceptible to failure as a result of stress, glucocorticoids, viral infections, abrupt exposure to cold air, and poor air quality. When some of these defenses fail, the lung can be colonized by bacterial pathogens that are equipped to evade the remaining defenses, resulting in the development of pneumonia. This review considers the mechanisms by which these predisposing factors compromise the defenses of the lung, with a focus on the development of bacterial pneumonia in cattle and supplemented with advances based on mouse models and the study of human disease. Deepening our understanding of how the respiratory defenses fail is expected to lead to interventions that restore these dynamic immune responses and prevent disease.

Critical assessment of an in vitro bovine respiratory organ culture system: a model of bovine herpesvirus-1 infection

A bovine in vitro organ culture (BIVOC) system was evaluated as a model to study host and pathogen events during the course of bovine herpesvirus-1 infection. Upper respiratory tract epithelium, from slaughtered animals, was cultured in an air-liquid interface system and integrity, viability, and TNF-alpha gene expression of tissue explants were monitored over 72h in the presence or absence of infection by bovine herpesvirus type 1 (BHV-1). Uninfected explants maintained viability and integrity over the 72h time course although histological signs of degeneration were first visible from 24h of culture. Explants were productively infected with BHV-1 and typical, dose dependent, cytopathic changes were observed in response to infection. Regulation of TNF-alpha gene expression in uninfected explants varied over time and was region-specific but there was significant down-regulation of TNF-alpha gene expression at 2h post-infection when compared to uninfected controls at the same time point. Taking caveats into consideration the BIVOC system shows promise as a tool for analysis of immediate or early events in host-pathogen interaction.

Endotoxin and Mammalian Host Responses During Experimental Disease

Endotoxin is an integral component of the outer membrane of Gram-negative bacteria and a prime example of unique and highly conserved bacterial surface molecules that engage with the innate immune system of the mammalian host via pattern recognition receptors on a range of host cells. The results of this interaction, which may be beneficial or detrimental to the development and welfare of the host, are reviewed, focusing on the different sensitivities and consequences in a range of hosts of experimental exposure to endotoxin, the disease outcomes and recent developments in our understanding of the mechanisms involved.

Effect of steroidal and non-steroidal anti-inflammatory drugs in combination with long-acting oxytetracycline on non-specific immunity of calves suffering from enzootic bronchopneumonia

The aim of this paper was to compare the effect of flumethasone and meloxicam in combination with oxytetracycline on clinical and immunological parameters of calves suffering from enzootic bronchopneumonia. The study was performed on 30 Black-and-White Lowland Breed calves with clinical signs of enzootic bronchopneumonia divided randomly into three equal groups and, respectively, treated with-Group I: oxytetracycline and meloxicam; Group II: oxytetracycline and flumethasone; Group III (control): oxytetracycline only. Treatment of calves with the combination of oxytetracycline and meloxicam (Group I) caused a significantly faster, in comparison to other groups, improvement in the clinical illness index score (CIIS: cough, nasal discharge, dyspnea, depression and anorexia) and a faster normalization of body temperature. A slow decrease in white blood cell (WBC) count, the number of neutrophils, MID (mixed number of monocytes, eosinophils and basophils) and in the individual number of monocytes (CD14/CD45 positive cells) was observed in Groups I and III. In the blood of the calves which received oxytetracycline and flumethasone (Group II), leukocytosis, neutrophilia and monocytosis with concomitant lymphopenia and a low number of T cells (CD2+) was observed. Moreover, the calves treated with flumethasone exhibited a decrease in gamma-globulin concentration, and phagocytic parameters. Both drugs, flumethasone and meloxicam slightly decreased tumor necrosis factor (TNF) but meloxicam slightly increased the levels of interferon (IFN) in sera and in bronchoalveolar lavages (BALs). These results suggest that the combination of meloxicam with an antibiotic in calves suffering from enzootic bronchopneumonia is superior to the antibiotic alone and also to the combination of the antibiotic with flumethasone.

Increased pulmonary secretion of tumor necrosis factor-alpha in calves experimentally infected with bovine respiratory syncytial virus

Bovine respiratory syncytial virus (BRSV) is an important cause of respiratory disease among calves in the Danish cattle industry. An experimental BRSV infection model was used to study the pathogenesis of the disease in calves. Broncho alveolar lung lavage (BAL) was performed on 28 Jersey calves, of which 23 were experimentally infected with BRSV and five were given a mock inoculum. The presence of the cytokine tumor necrosis factor alpha (TNF-alpha) in the BAL fluids was detected and quantified by a capture ELISA. TNF-alpha was detected in 21 of the infected animals. The amount of TNF-alpha in the BAL fluid of calves killed post inoculation day (PID) 2 and 4 was at the same very low level as in the uninfected control animals. Large amounts of TNF-alpha were detected on PID 6, maximum levels of TNF-alpha were reached on PID 7, and smaller amounts of TNF-alpha were seen on PID 8. The high levels of TNF-alpha appeared on the days where severe lung lesions and clinical signs were obvious and the amounts of BRSV-antigen were at their greatest. Although Pasteurellaceae were isolated from some of the BRSV-infected calves, calves treated with antibiotics before and through the whole period of the infection, as well as BRSV-infected calves free of bacteria reached the same level of TNF-alpha as animals from which bacteria were isolated from the lungs. It is concluded that significant quantities of TNF-alpha are produced in the lungs of the calves on PID 6-7 of BRSV infection. The involvement of TNF-alpha in the pathogenesis of, as well as the anti-viral immune response against, BRSV infection is discussed.

The effect of steroidal and non-steroidal anti-inflammatory drugs on the cellular immunity of calves with experimentally-induced local lung inflammation

We examined the effect of a single intravenous dose of flumetasone (SAID) and meloxicam (NSAID) treatment of calves with experimentally-induced localized lung inflammation on immunological and hematological variables such as total protein, gamma globulin, hemoglobin (Hb) concentrations, alkaline phosphatase activity, packed red cell volume (PCV), red blood cell (RBC) and white blood cell (WBC) counts. The influence of drug treatment on the phagocytic activity of WBC and bronchoalveolar lavage (BAL) cells and their ex vivo ability to produce interferon (IFN) and tumor necrosis factor (TNF) after induction with Newcastle disease virus (NDV), as well as on the development of PHA-induced skin delayed hypersensitivity reaction was also determined. Two days after the treatment of calves with experimentally-induced local lung inflammation with flumetasone (5 mg per calf), we observed a significant increase in WBC count, especially neutrophils, and a decrease in gamma globulin concentration, in the percent of blood phagocytic cells and their random migration. Flumetasone treatment also inhibited the development of skin delayed hypersensitivity reaction. In contrast, the treatment of calves with meloxicam (50 mg per calf) did not influence any hematological parameters or skin reactivity. Both drugs, flumetasone and meloxicam, influenced TNF production in ex vivo cultures of blood and BAL cells, inhibiting excessive TNF production induced by local lung inflammation. Contrary to TNF, the treatment of calves with meloxicam and flumetasone enhanced ex vivo IFN production in blood and BAL cells. Histological examination of lung tissue revealed that in control calves (those not treated with anti-inflammatory drugs) and in calves treated with flumetasone, symptoms of stromo-purulent inflammation of pulmonary tissue developed. However, in calves treated with meloxicam, only interstitial inflammation with a slight thickening of interalveolar septa and infiltration of lymphoid cells was observed. These results suggest that in this model of pneumonia, it is more appropriate to use a single dose of meloxicam, rather than flumetasone, to modulate lung inflammation.

Tumor necrosis factor and interferon activity in the circulation of calves after repeated injection of low doses of lipopolysaccharide

The effect of two intravenous (i.v.) injections of low doses of lipopolysaccharide (LPS)(0.1 microgram/kg of body weight) administered at 7-day intervals on the systemic release of tumor necrosis factor (TNF) and interferon (IFN), on the rectal temperature, breathing and heart rate, and on packed cell volume (PCV), plasma glucose concentration, white blood cell (WBC) counts in 3-week-old calves, was estimated. The first injection of LPS caused a significant increase in breathing and heart rate, rectal temperature, prolonged hypoglycemia and leukopenia, but no significant changes in PCV were observed. TNF and IFN activity peaked at 2 h after LPS injection and disappeared from circulation by 4 h and 5 h, respectively. After the second injection of LPS, the reaction of calves was similar to that observed after the first injection, however, the breathing rate and TNF systemic production were significantly reduced. The results obtained indicate that a low dose of LPS leads to the development of 'late' tolerance manifested by hyporeactivity to TNF production but with maintained responsivity to IFN production, pyrogenic, hypoglycemic and leukemic response to the second injection of LPS. In conclusion, these results demonstrate that the tolerance response is not universal to all hematologic and immunologic parameters, and that the response needs to be evaluated with respect to the specific variable.

Protective effect of passive immunization against TNF-alpha in mice infected with Sendai virus

TNF-alpha has been reported to be induced in mice infected with Sendai virus. We evaluated the role of TNF-alpha in the virus infection. TNF-alpha was induced locally in proportion to virus titers in the lung. The activity was correlated with suppression of body weight gain. Passive immunization against TNF-alpha improved body weight gain and ameliorated pneumonic lesions in infected mice, and prevented them from lethal infection, but lung virus induced emaciation, pneumonic lesions and death were mediated by TNF-alpha.

Induction of procoagulant activity in virus infected bovine alveolar macrophages and the effect of lipopolysaccharide

Three viruses known to be associated with the bovine respiratory disease complex were evaluated in vitro for potential impact upon the procoagulant activity (PCA) of bovine alveolar macrophages (bAM). Cultures of bAM were inoculated with bovine parainfluenza virus Type 3 (PI-3), cytopathic bovine viral diarrhea virus (cpBVDV), non-cytopathic BVDV (ncpBVDV), or bovine herpes virus Type 1 (BHV-1) and incubated for several time periods (24, 48, 72, 96 h). BAM were then exposed to E. coli lipopolysaccharide (LPS), or LPS with bovine serum. The amount of PCA expressed was quantified using a chromogenic assay. Viral inoculation increased bAM expression of PCA (P < 0.01). The increase in PCA expression was larger at higher rates of viral inoculation (P < 0.01). LPS enhanced PCA expression by bAM at low rates of viral inoculation (P < 0.01). The effect of LPS-serum treatment was greater than the LPS alone (P < 0.01). At high rates of viral inoculation, LPS had no enhancing effect on PCA expression. The effect of LPS on virus inoculated bAM varied with virus type, rate of inoculation, and duration of virus exposure (P < 0.01). The results suggest that these four viruses initiate the production of PCA by bAM independently of LPS. In the field situation, an initial viral infection may induce fibrin deposition in the pulmonary alveoli prior to the establishment of a secondary gram negative bacterial infection.

Effects of BHV-1 on PMN adhesion to bovine lung endothelial cells

Bovine herpes virus-1 (BHV-1) infection appears to decrease the rate of polymorphonuclear leukocyte (PMN) influx into the lung in response to the secondary invader, Pasteurella haemolytica. It was postulated that BHV-1 may affect the rate of cellular infiltration by altering the function of the endothelium, thereby preventing PMN movement across the blood-tissue barrier. Therefore, we decided to investigate the effect of BHV-1 on the ability of PMN to adhere to lung endothelial cells (LEC). LEC were isolated from fetal bovine fetal tissue and were shown to function in PMN adhesion assays. Furthermore, enhanced PMN adhesion was observed after exposure of LEC to recombinant bovine TNF-alpha (rBoTNF-alpha) for 4, 8, 12, and 24 h. LEC infected with BHV-1 were shown to be less responsive to rBoTNF-alpha. However, infection of LEC with BHV-1 at an multiplicity of infection (MOI) of 1.0 or 10 did not affect basal levels of PMN adhesion to these cells. Decreased PMN binding to BHV-1-infected LEC, simultaneously treated with rBoTNF-alpha, was observed at 10-12 h post-infection. The data suggest that BHV-1 may prevent cytokine-induced PMN infiltration of the lung through the modification of EC responses to cytokines.

Wool and grain dusts stimulate TNF secretion by alveolar macrophages in vitro

OBJECTIVE

The aim of the study was to investigate the ability of two organic dusts, wool and grain, and their soluble leachates to stimulate secretion of tumour necrosis factor (TNF) by rat alveolar macrophages with special reference to the role of lipopolysaccharide (LPS).

METHODS

Rat alveolar macrophages were isolated by bronchoalveolar lavage (BAL) and treated in vitro with whole dust, dust leachates, and a standard LPS preparation. TNF production was measured in supernatants with the L929 cell line bioassay.

RESULTS

Both wool and grain dust samples were capable of stimulating TNF release from rat alveolar macrophages in a dose-dependent manner. The standard LPS preparation caused a dose-dependent secretion of TNF. Leachates prepared from the dusts contained LPS and also caused TNF release but leachable LPS could not account for the TNF release and it was clear that non-LPS leachable activity was present in the grain dust and that wool dust particles themselves were capable of causing release of TNF. The role of LPS in wool dust leachates was further investigated by treating peritoneal macrophages from two strains of mice, LPS responders (C3H) and LPS non-responders (C3H/HEJ), with LPS. The non-responder mouse macrophages produced very low concentrations of TNF in response to the wool dust leachates compared with the responders.

CONCLUSIONS

LPS and other unidentified leachable substances present on the surface of grain dust, and to a lesser extent on wool dust, are a trigger for TNF release by lung macrophages. Wool dust particles themselves stimulate TNF. TNF release from macrophages could contribute to enhancement of inflammatory responses and symptoms of bronchitis and breathlessness in workers exposed to organic dusts such as wool and grain.

Quantitation of bovine TNF-alpha mRNA by reverse transcription and competitive polymerase chain reaction amplification

A reverse transcription (RT) and competitive polymerase chain reaction (PCR) amplification technique was developed to quantify bovine tumor necrosis factor-alpha (TNF-alpha) mRNA. A bovine TNF-alpha cDNA insert containing plasmid was used to produce a 237-bp cDNA competitive template which, when PCR-amplified with primers designed to amplify bovine TNF-alpha cDNA, resulted in a 147-bp product distinguishable by agarose gel electrophoresis from the 378-bp TNF-alpha RT-PCR-amplified cDNA product. Dilutions of competitive template were co-amplified with constant amounts of total cellular RNA harvested from bovine alveolar macrophages (BAM). Products were separated in ethidium-bromide-stained agarose gels and relative amounts of TNF-alpha mRNA were determined by densitometric scanning of TNF-alpha cDNA and competitive template product bands on photographic negatives. Digestions with Pvu II and Sty I restriction endonucleases verified that RT-PCR-amplified TNF-alpha cDNA products were authentic. A time study indicated that TNF-alpha mRNA concentrations peaked 3 h after endotoxin and virus induction of BAMs.

Differential binding of bacterial lipopolysaccharide to bovine peripheral-blood leukocytes

The response of mammalian monocytes and macrophages to bacterial lipopolysaccharide (LPS) may be influenced by serum factors that increase or decrease the propensity of LPS to bind to cell surfaces. We used fluorescence flow cytometric analysis to investigate the capability of bovine peripheral-blood leukocytes to bind LPS in the presence or absence of bovine serum. At all concentrations of FITC-LPS tested (LPS from E. coli 0111:B4; 10 ng/ml, 100 ng/ml, 1 micrograms/ml), monocytes, lymphocytes, and granulocytes bound more FITC-LPS in the presence of 10% bovine serum than in serum-free conditions (P < 0.01). At the intermediate concentration tested (100 ng/ml), monocytes displayed a relative fluorescence intensity (RFI) of 2.27 +/- 1.24 units without serum and 17.48 +/- 8.05 with 10% serum. Values for granulocytes were similar to those of monocytes, 3.55 +/- 1.31 without and 19.24 +/- 6.93 with serum, and values for lymphocytes were 1.89 +/- 0.47 RFI units without serum and 6.27 +/- 2.61 RFI units with serum. At 10 ng/ml and 1 microgram/ml FITC-LPS the RFI of monocytes and granulocytes were also similar and not significantly different, and both bound significantly more LPS than lymphocytes (P < 0.01). When 100 ng/ml FITC-LPS was coincubated with leukocytes, 10% serum, and a 100-fold excess of unlabeled LPS, the amount of FITC-LPS bound to monocytes was reduced from 23.99 to 7.23 RFI units (P < 0.01), reduced from 22.00 to 7.30 RFI units with granulocytes (P < 0.05), and reduced from 7.51 to 2.29 RFI units (P < 0.10) with lymphocytes. These data demonstrate that factors in bovine serum significantly amplify the association of LPS with peripheral-blood leukocytes and that increased binding of LPS is greatest with monocytes and granulocytes.