Pharmacological inhibition of Mannheimia haemolytica lipopolysaccharide and leukotoxin-induced cytokine expression in bovine alveolar macrophages

The Effects of Ursolic Acid Treatment on Immunopathogenesis Following Mannheimia haemolytica Infections

Bovine respiratory disease complex (BRDC) is a costly economic and health burden for the dairy and feedlot cattle industries. BRDC is a multifactorial disease, often involving viral and bacterial pathogens, which makes it difficult to effectively treat or vaccinate against. Mannheimia haemolytica (MH) are common commensal bacteria found in the nasopharynx of healthy cattle; however, following environmental and immunological stressors, these bacteria can rapidly proliferate and spread to the lower respiratory tract, giving rise to pneumonic disease. Severe MH infections are often characterized by leukocyte infiltration and dysregulated inflammatory responses in the lungs. IL-17A is thought to play a key role in this inflammatory response by inducing neutrophilia, activating innate and adaptive immune cells, and further exacerbating lung congestion. Herein, we used a small molecule inhibitor, ursolic acid (UA), to suppress IL-17A production and to determine the downstream impact on the immune response and disease severity following MH infection in calves. We hypothesized that altering IL-17A signaling during MH infections may have therapeutic effects by reducing immune-mediated lung inflammation and improving disease outcome. Two independent studies were performed (Study 1 = 32 animals and Study 2 = 16 animals) using 4-week-old male Holstein calves, which were divided into 4 treatment group including: (1) non-treated and non-challenged, (2) non-treated and MH-challenged, (3) UA-treated and non-challenged, and (4) UA-treated and MH-challenged. Based on the combined studies, we observed a tendency (p = 0.0605) toward reduced bacterial burdens in the lungs of UA-treated animals, but did not note a significant difference in gross (p = 0.3343) or microscopic (p = 0.1917) pathology scores in the lungs. UA treatment altered the inflammatory environment in the lung tissues following MH infection, reducing the expression of IL-17A (p = 0.0870), inflammatory IL-6 (p = 0.0209), and STAT3 (p = 0.0205) compared to controls. This reduction in IL-17A signaling also appeared to alter the downstream expression of genes associated with innate defenses (BAC5, DEFB1, and MUC5AC) and lung remodeling (MMP9 and TIMP-1). Taken together, these results support our hypothesis that IL-17A signaling may contribute to lung immunopathology following MH infections, and further understanding of this inflammatory pathway could expand therapeutic intervention strategies for managing BRDC.

Pulmonary and systemic responses to aerosolized lysate of Staphylococcus aureus and Escherichia coli in calves

Background

Constitutive and inducible defenses protect the respiratory tract from bacterial infection. The objective of this study was to characterize the response to an aerosolized lysate of killed bacteria, as a basis for studying the regulation and in vivo effects of these inducible innate immune responses.

Results

Bacterial lysate consisting of heat-killed and sonicated Staphylococcus aureus and Escherichia coli was aerosolized to 6 calves and systemic and pulmonary innate immune and inflammatory responses were measured in the first 24 h relative to baseline. Evaluated parameters included clinical parameters (body temperature and heart and respiratory rates), blood acute phase proteins and leukocyte counts, and leukocytes and proteins in bronchoalveolar lavage fluid. Mild clinical signs with increased heart rates and rectal temperatures developed following administration of the lysate, with resolution by 24 h. Serum haptoglobin and plasma fibrinogen concentrations were elevated at 24 h relative to baseline. Bronchoalveolar lavage fluid (BALF) had increased cellularity and increased proportion of neutrophils, as well as higher concentrations of interleukin (IL)-8, IL-10 and total protein at 24 h relative to baseline. Mass spectrometry identified 965 unique proteins in BALF: 19 proteins were increased and 26 proteins were decreased relative to baseline. The upregulated proteins included those involved in innate immunity including activation of complement, neutrophils and platelets. At postmortem examination, calves receiving higher doses of lysate had areas of lobular consolidation and interlobular edema. Histologically, neutrophils were present within bronchioles and to a lesser extent within alveoli. Calves receiving highest doses of lysate had patchy areas of neutrophils, hemorrhage and hyaline membranes within alveoli.

Conclusions

Aerosolization of bacterial lysate stimulated an innate immune response in lungs and airways, with alveolar damage observed at higher doses. Such a stimulus could be of value for investigating the effects of inducible innate immune responses on occurrence of disease, or for evaluating how stress, drugs or genetics affect these dynamic responses of the respiratory tract.

IL-1R and Inflammasomes Mediate Early Pulmonary Protective Mechanisms in Respiratory Brucella Abortus Infection

Brucella spp. infection is frequently acquired through contaminated aerosols. The role of interleukin-1 beta (IL-1β) in the early pulmonary response to respiratory Brucella infection is unknown. As shown here, IL-1β levels in lung homogenates and bronchoalveolar lavage fluid (BALF) of mice intratracheally inoculated with B. abortus were increased at 3 and 7 days p.i. At 7 days p.i., pulmonary CFU numbers were higher in IL-1 receptor (IL-1R) knockout (KO) mice than in wild type (WT) mice. At different times p.i. CFU in lungs and BALF were higher in mice lacking some inflammasome components (caspase-1, AIM2, NLRP3) than in WT mice. At 2 days p.i. pulmonary levels of IL-1β and CXCL1 (neutrophils chemoattractant) were lower in caspase-1/11 KO mice. At day 3 p.i., neutrophils counts in BALF were lower in caspase-1/11 KO mice than in WT mice. During in vitro infections, IL-1β secretion was lower in alveolar macrophages from caspase-1/11, NLRP3 or AIM2 KO mice than in WT controls. Similarly, IL-1β production by B. abortus-infected alveolar epithelial cells was reduced by pretreatment with a specific caspase-1 inhibitor. This study shows that IL-1R, probably through IL-1β action, and the NLRP3 and AIM2 inflammasomes are involved in pulmonary innate immune protective mechanisms against respiratory B. abortus infection.

Improvement of pregnancy rate by intrauterine administration of dexamethasone and recombinant human leukemia inhibitory factor at the time of embryo transfer in cattle

Bovine embryos (day 5) were cultured to day 10 with or without 100 ng/mL PGF2α in medium supplemented with control; 100 nM Dex; 1,000 U/mL recombinant human leukemia inhibitory factor (rhLIF); or Dex+rhLIF. Although the rates to development to the blastocyst were not significantly different among groups, the hatching rate after additional culture with Dex +/or rhLIF was significantly higher in all supplemented groups than the control (p < 0.05). In the presence of PGF2α, the hatching rate was significantly restored in all supplemented groups relative to the group treated with only PGF2α and the control (p < 0.05). Embryo transfer (ET) was performed with blastocysts (day 7). PGF2α levels of control recipient cows were significantly higher in the circulatory blood samples collected 60 min after ET than in samples collected 60 min before ET (p < 0.005), and were decreased in cows injected with loading medium supplemented with Dex+rhLIF (p < 0.005). Pregnancy rate was significantly higher in the ET group that received supplemented embryo-loading medium than in the non-supplemented control (p < 0.05). The intrauterine administration of Dex and rhLIF at ET prevented increased PGF2α in circulatory blood and resulted in enhanced pregnancy rate.

Characterization of the contributions of Hp-MMP 9 to the serum acute phase protein response of lipopolysaccharide challenged calves

Background

Bovine respiratory disease (BRD) is a costly feature of modern cattle production. Early and accurate detection of BRD may prove useful in the successful management of this disease. The primary objective of the study was to define the time course of covalent complexes of neutrophil, haptoglobin (Hp) and matrix metalloproteinase 9 (Hp-MMP 9) in serum after intravenous lipopolysaccharide (LPS) in comparison to traditional markers. Our hypothesis was that serum concentrations of neutrophil Hp-MMP 9 provides information distinct from traditional acute phase protein markers. To characterize the neutrophil responses to lipopolysaccharide (E. coli; O111:B4; 2.5 μg/kg body weight), nine healthy, Jersey calves (65-82 days of age; 74.5 ± 13.1 kg) were challenged and physiologic parameters, peripheral blood cell counts and serum cortisol (C), Hp-MMP 9, Hp, alpha₁-acid glycoprotein (AGP), serum amyloid A (SAA) were obtained starting 24 hours before to 96 hours post-LPS challenge.

Results

Physiologic parameters (temperature, pulse, respiratory rate) and attitude assessed at each time point indicated that LPS challenge resulted in rapid onset of depression, tachypnea, leukopenia, neutropenia and lymphopenia within 1 hour. Serum C concentrations were significantly increased by 1 hour post-LPS. Serum Hp-MMP 9 complexes were detectable in serum by 0.5 hours and peaked at 16 h, serum total Hp remained <10 μg/mL until 8 hours post LPS infusion and were significantly greater than baseline by 12 hours post-LPS infusion. Serum amyloid A concentrations increased significantly by 8 hours post LPS. Serum concentrations of AGP increased significantly by 16 hours post LPS. Serum concentrations of Hp, SAA and AGP remained significantly greater than baseline out to 96 hours post-LPS. The total systemic exposure to traditional makers is significantly greater than from Hp-MMP 9

Conclusion

Using a well described model for acute phase protein responses, the data demonstrate that serum neutrophil Hp-MMP 9 complexes appear sooner and decline more rapidly than other acute phase proteins (APP). Since Hp-MMP9 is stored pre-formed, it provides information specifically addressing the LPS-induced activation of bovine neutrophils. Contributions of Hp-MMP 9 to the serum acute phase protein response may provide useful information, independent of hepatic responses, in diagnosis of acute inflammation.

Neutrophil gelatinase-associated lipocalin (NGAL) and insulin-like growth factor (IGF)-1 association with a Mannheimia haemolytica infection in sheep

This study was aimed at mapping the tissue distribution of some inflammatory parameters associated with a Mannheimia haemolytica (M. haemolytica) infection in sheep. The M. haemolytica was isolated and characterized from the affected lungs of slaughtered animals. Cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-10, insulin-like growth factor (IGF)-1, as well as the acute-phase protein, neutrophil gelatinase-associated lipocalin (NGAL), were identified in the lung tissues, the serum, and the lymph nodes of M. haemolytica infected sheep, by enzyme-linked immunosorbent assay (ELISA). NGAL and IGF-1 pointed to an innate immune response, and epithelial cell repairing, respectively. The adaptive immune response was identified through the type of cytokines present in the affected sheep, as TNF-α represents the pro-inflammatory cytokines, and IL-10 represents the anti-inflammatory cytokines. M. haemolytica isolates were confirmed by polymerase chain reaction (PCR) and DNA sequences. There was a significant difference in the concentrations of NGAL, IGF-1, TNF-α, and IL-10, as observed in the affected sheep when compared to the healthy sheep. This study, for the first time, closely describes the distribution of some key and new inflammatory parameters in the tissue homogenate of affected lungs.

A sesquiterpenol extract potently suppresses inflammation in macrophages and mice skin and prevents chronic liver damage in mice through JNK-dependent HO-1 expression

This study aimed to elucidate the anti-inflammatory and hepatoprotective bioactivities of a sesquiterpenol, (1S,6R)-2,7(14),10-bisabolatrien-1-ol-4-one (BSL), isolated from Cryptomeria japonica (Taxodiaceae) wood extract. BSL markedly suppressed TNF-α and IL-6 secretion, PGE(2) production, and mRNA expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), in lipopolysaccharide (LPS)-stimulated mouse macrophages. BSL also potently inhibited the 12-O-tetradecanoylphorbol-13-acetate (TPA) induced protein levels of nitrotyrosine and COX-2 in mouse skin with dermatitis. Conversely, the stress protein heme oxygenase-1 (HO-1) was found upregulated in the same BSL-treated macrophages, probably through activation of the JNK-dependent pathway. LPS-induced activation of NF-κB and mitogen-activated protein kinase signaling pathways, however, was not responsive to BSL treatment. A BSL-enriched extract (BSL-E; 10mg/kg) significantly prevented CCl(4)-induced chronic liver injury, lipid accumulation, and cell necrosis and inhibited aminotransferase activities and iNOS and COX-2 overexpression in mice liver tissues, an effect comparable with that of silymarin, a hepatoprotective drug.

Comparative metabolomics approach coupled with cell- and gene-based assays for species classification and anti-inflammatory bioactivity validation of Echinacea plants

Echinacea preparations were the top-selling herbal supplements or medicines in the past decade; however, there is still frequent misidentification or substitution of the Echinacea plant species in the commercial Echinacea products with not well chemically defined compositions in a specific preparation. In this report, a comparative metabolomics study, integrating supercritical fluid extraction, gas chromatography/mass spectrometry and data mining, demonstrates that the three most used medicinal Echinacea species, Echinacea purpurea, E. pallida, and E. angustifolia, can be easily classified by the distribution and relative content of metabolites. A mitogen-induced murine skin inflammation study suggested that alkamides were the active anti-inflammatory components present in Echinacea plants. Mixed alkamides and the major component, dodeca-2E,4E,8Z,10Z(E)-tetraenoic acid isobutylamides, were then isolated from E. purpurea root extracts for further bioactivity elucidation. In macrophages, the alkamides significantly inhibited cyclooxygenase 2 (COX-2) activity and the lipopolysaccharide-induced expression of COX-2, inducible nitric oxide synthase and specific cytokines or chemokines [i.e., TNF-α, interleukin (IL)-1α, IL-6, MCP-1, MIP-1β] but elevated heme oxygenase-1 protein expression. Cichoric acid, however, exhibited little or no effect. The results of high-performance liquid chromatography/electron spray ionization/mass spectrometry metabolite profiling of alkamides and phenolic compounds in E. purpurea roots showed that specific phytocompound (i.e., alkamides, cichoric acid and rutin) contents were subject to change under certain post-harvest or abiotic treatment. This study provides new insight in using the emerging metabolomics approach coupled with bioactivity assays for medicinal/nutritional plant species classification, quality control and the identification of novel botanical agents for inflammatory disorders.

Thalidomide: mechanisms of action

The classification of thalidomide as an orphan drug with anti-inflammatory actions has led to its off-label use in conditions refractory to other medications. Although the observed clinical effects of thalidomide suggest it to have immunomodulatory capabilities, the mechanism of action is unclear. Here we review both the positive and negative studies of thalidomide at the bench in order to improve our understanding of the possible mechanisms of this drug in treating a variety of diseases at the bedside. Studies on the effects of thalidomide on the innate and adaptive immune system as well as tumorigenesis and angiogenesis are discussed.

Pentoxifylline does not improve outcome in a murine model for the multiple-organ dysfunction syndrome

OBJECTIVE

To investigate the effects of pentoxifylline (PTX) administration in a murine model for the multiple-organ dysfunction syndrome (MODS).

DESIGN AND SETTING

Prospective double-blind randomized animal study in a university research laboratory.

INTERVENTIONS AND MEASUREMENTS

Sixty C57BL/6 mice were given an aseptic intraperitoneal injection of lipopolysaccharide followed after 6 days by zymosan (day 0) at a dose of either 0.9 or 1.0 mg/g body weight. Starting on day 0 mice were administered PTX at a dose of 80 mg/kg body weight or saline per os every 8 h. On day 17 surviving animals were killed, and their liver, lungs, spleen, and kidneys were collected.

RESULTS

Mortality, course of body temperature, body weight, and macroscopic lung damage were similar between zymosan-treated groups. Administration of PTX did not significantly alter survival, body temperature, body weight, or macroscopic lung damage. In addition, there were no significant differences in organ weights between mice that received PTX and mice that received PBS. Although PTX inhibited the lipopolysaccharide-induced increase in tumor necrosis factor alpha and interleukin 6 expression (but not interleukin 1beta expression) at both mRNA and protein level in a murine macrophage cell line, tumor necrosis factor alpha mRNA expression in the livers of PTX-treated mice was not significantly inhibited.

CONCLUSIONS

The results reported here do not support the hypothesis that PTX improves outcome in zymosan-induced multiple-organ dysfunction in mice.

Protective effect of dexamethasone in experimental bovine pneumonic mannheimiosis

Clinical and experimental studies provide unequivocal evidence that neutrophils participate in the pathogenesis of lung injury in bovine pneumonic mannheimiosis (BPM). Since the inflammatory cytokines tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-8 play a central role in the recruitment and activation of neutrophils, we hypothesize that pharmacological inhibition of their expression may prevent or reduce the inflammatory lung injury that is characteristic of the disease. The purpose of this study was to determine whether systemic therapy with dexamethasone sodium phosphate (DEX), a potent inhibitor of inflammatory cytokine synthesis, ameliorates disease development in an in vivo experimental model of BPM. Four experimental calves were treated intravenously with DEX (2 mg/kg 6 h prior to infection, 2 mg/kg immediately prior to infection, and 1 mg/kg every 12 h thereafter), while two placebo-treated control calves received dose-matched volumes of sterile saline. Disease was induced in the left lungs of the six calves by endobronchial administration of Mannheimia haemolytica. Clinical disease was characterized using a non-parametric scoring system, and the extent of gross pulmonary pathology affecting the left lung 48 h post-infection (PI) was determined using morphometric methods. Disease scores for DEX-treated calves were significantly lower than those for placebo-treated controls at all time points beyond 2 h PI (P<0.05) and the percent volume of the left lung exhibiting gross pneumonic lesions was significantly lower in DEX-treated calves (6.0+/-1.1%) as compared to controls (68.9+/-13.3%), P<0.05. In addition, histopathological lesions were less severe and extensive in DEX-treated calves. These findings indicate that pharmacological modulation of pulmonary inflammation may represent an alternative approach to control this disease. Successful implementation of this strategy will require additional research to identify drug agents that target the expression of cytokines and other inflammatory mediators without compromising host immune responses.