Molecular cloning and functional expression of equine interleukin-1 receptor antagonist

Inflammatory mediators are potential biomarkers for extracorporeal shockwave therapy in horses

BACKGROUND

Extracorporeal shockwave therapy (ESWT) can potentially mask painful injuries in equine athletes. Tests to detect whether a horse has received ESWT prior to competition are needed. Extracorporeal shockwave therapy is known to affect inflammatory mediators in other species, and if these mediators are altered in the horse, these could serve as biomarkers of ESWT.

OBJECTIVES

To test the hypothesis that a single application of ESWT will alter the circulating protein concentrations of 10 inflammatory mediators in horse plasma.

STUDY DESIGN

Prospective repeated measures experimental study.

METHODS

Eleven healthy horses were administered a single dose of ESWT on the dorsal surface of proximal MCIII. Blood samples were collected at -168, -144, -120, -96, -72, -70, -68, -66, -48, -24, -6, -4, -2, 0 h before and 2, 4, 6, 24, 48, 72, 96, 168, 336 and 504 h after ESWT. Plasma concentrations of interleukin 1 beta (IL-1β), IL-1 receptor antagonist (IL-1RA), IL-2, IL-4, IL-6, IL-10, IL-15, interferon gamma (IFN-γ), soluble toll-like receptor 2 (sTLR2) and tumour necrosis factor alpha (TNF-α) were measured to assess the effects of ESWT on these mediators.

RESULTS

Baseline concentrations of inflammatory mediators did not change substantially during the week prior to ESWT. Plasma concentrations of five inflammatory factors changed following ESWT. IL-1β and IL-6 were significantly down-regulated (P<0.01), while TNF-α, IL-1RA and TLR2 were significantly up-regulated (P<0.01). The remaining cytokines were not significantly affected by ESWT.

MAIN LIMITATIONS

This study was performed in a small number of sedentary, healthy pasture-kept horses using a single dose of ESWT applied to a single location. Additional studies are necessary to determine the effect of ESWT on inflammatory mediators in athletic horses undergoing treatment for musculoskeletal injuries.

CONCLUSIONS

Plasma concentrations of TNF-α, IL-1β, IL-1RA, IL-6 and TLR2 were significantly affected by ESWT, and deserve further investigation as possible biomarkers of ESWT.

Evaluation of the reactivity of commercially available monoclonal antibodies with equine cytokines

Research on equine cytokines is often performed by analyses of mRNA. For many equine cytokines an analysis on the actual protein level is limited by the availability of antibodies against the targeted cytokines. Generation of new antibodies is ongoing but time consuming. Thus, testing the reactivity of commercially available antibodies for cross-reactivity with equine cytokines is of particular interest. Fifteen monoclonal antibodies against IL-1β, IL-6, IL-8, IL-12, IL-18 and Granulocyte Macrophage Colony stimulating factor (GM-CSF) of different species were evaluated for reactivity with their corresponding equine cytokines. Dot Blot (DB) and Western Blot (WB) analyses were performed using recombinant equine cytokines as positive controls. Immunohistochemistry (IHC) was carried out on equine tissue and flow cytometry on equine PBMC as positive controls. As expected, three equine IL-1β antibodies detected equine IL-1β in DB, WB and IHC. For these, reactivity in IHC has not been described before. One of them was also found to be suitable for intracellular staining of equine PBMC and flow cytometric analysis. Two antibodies raised against ovine GM-CSF cross-reacted with equine GM-CSF in DB, WB and IHC. For these anti-GM-CSF mAbs this is the first experimental description of cross-reactivity with equine GM-CSF (one mAb was predicted to be cross-reactive in WB in the respective data sheet). The other clone additionally proved to be appropriate in flow cytometric analysis. Two mAbs targeting porcine IL-18 cross-reacted in IHC, but did not show specificity in the other applications. No reactivity was shown for the remaining five antibodies in DB, although cross-reactivity of two of the antibodies was described previously. The results obtained in this study can provide beneficial information for choosing of antibodies for immunological tests on equine cytokines.

Clinical and immunologic assessment of sepsis and the systemic inflammatory response syndrome in cats

OBJECTIVE

To compare clinical findings and inflammatory mediator production among cats with sepsis, cats with noninfectious systemic inflammatory response syndrome (SIRS), and healthy cats.

DESIGN

Case-control study.

ANIMALS

Cats with sepsis (n = 16) or SIRS (19) and 8 healthy control cats.

PROCEDURES

Clinical variables were recorded for each cat, and plasma tumor necrosis factor (TNF) and interleukin (IL)-1β activities and IL-6 and CXC chemokine ligand (CXCL)-8 concentrations were determined at initial evaluation.

RESULTS

Clinicopathologic abnormalities associated with sepsis in cats included a high band neutrophil percentage, eosinopenia, hyponatremia, hypochloremia, hypoalbuminemia, hypocalcemia, and hyperbilirubinemia. When the sepsis and SIRS groups were compared, the only significant differences in the CBC and plasma biochemical findings were band neutrophil percentage and albumin concentration. Cats with sepsis had significantly greater plasma TNF activity than did healthy cats and were more likely to have detectable concentrations of IL-6 than were cats with SIRS or healthy cats. Plasma IL-1β activity did not differ among groups, and CXCL-8 was not detectable in most (32/43) cats. Mortality rate was not significantly greater for cats with sepsis (7/16) than for cats with SIRS (5/19). Plasma IL-1β activity and IL-6 and chloride concentrations were the only variables correlated with nonsurvival in the sepsis group.

CONCLUSIONS AND CLINICAL RELEVANCE

Cats with sepsis may have various clinicopathologic abnormalities but are more likely to have a high band neutrophil percentage and hypoalbuminemia than cats with noninfectious SIRS. Plasma interleukin-1β activity and plasma IL-6 and chloride concentrations may be useful prognostic biomarkers for septic cats.

Pathogen associated molecular pattern-induced TNF, IL-1β, IL-6 and CXCL-8 production from feline whole blood culture

Whole blood culture (C(wb)) is a method to evaluate leukocyte response to stimuli. We used C(wb) to evaluate the inflammatory response to pathogen associated molecular patterns (PAMPs) in cats. Blood was collected from diluted with RPMI and stimulated with various concentrations of lipopolysaccharide (LPS), lipoteichoic acid (LTA), peptidoglycan (PG) or control (PBS). Multiple concentrations of LPS, LTA and PG significantly stimulated tumor necrosis factor (TNF), interleukin (IL)-1β and CXC chemokine ligand (CXCL)-8 in feline C(wb). All PAMPs failed to stimulate IL-6 production and PG failed to stimulate CXCL-8 production. Lipopolysaccharide was a more potent inducer of IL-1β and CXCL-8 than LTA or PG and LTA is a more potent inducer of CXCL-8 than PG. Based on these data, PAMPs from gram positive and negative bacteria induce TNF, IL-1β and CXCL-8 production in feline whole blood. Cats appear to be relatively more sensitive to gram negative compared to gram positive bacteria.

A rapid and simple method for the separation of pure lymphocytes from horse blood

A method for the separation of pure and viable lymphocytes and granulocytes from the same blood sample in horses was reported. By centrifuging equine heparinized blood at 100 xg for 10 min at room temperature (r.t.), the resulting supernatant plasma was an almost pure (97.71 +/- 0.30%; n = 15) suspension of highly viable (98.72 +/- 0.28%) lymphocytes. When sodium citrate was used as an anticoagulant, lymphocyte suspensions collected in the same manner showed lower purity (87.89 +/- 1.59%; n = 9) and higher yields (56.56 +/- 3.89%, n = 9 versus 36.11 +/- 2.23%, n = 15). Where needed, a further centrifugation at 250 xg for 3 min (r.t.) of heparinized lymphocyte preparations removed an average of 87.39% (n = 15) contaminating platelets. A suspension of 85.96 +/- 2.20% pure granulocytes (93.23 +/- 1.74% neutrophils; n = 14) with minimal contamination by erythrocytes and high viability (93.11 +/- 1.26%) was obtained by performing a flash red blood cell lysis on the white-greyish layer resulting from the centrifugation of the heparinized blood samples. Among the several methods available, the procedure described herein is easy, rapid, cheap and reproducible.

Cloning of canine IL-1ra, TNFR and TIMP-2

This paper describes the cloning and sequence analysis of the cDNA's encoding the canine homologues of interleukin-1 receptor antagonist (IL-1ra), tumour necrosis factor receptor extra-cellular domain (TNFR/ECD) and tissue inhibitor of metalloproteinase-2 (TIMP-2). The coding sequences for canine IL-1ra and TNFR/ECD were obtained using reverse transcription polymerase chain reaction (RT-PCR) using RNA harvested from canine peripheral blood mononuclear cells (PBMC) and TIMP-2 was isolated in a similar fashion from the canine D17 osteosarcoma cell line. Sequence analysis of the canine genes demonstrated open reading frames of 531, 633 and 663 base pairs (bp), respectively. All three canine proteins IL-1ra, TNFR/ECD and TIMP-2 (177, 211 and 221 amino acids, respectively) showed considerable sequence similarity with the homologous sequences published for other species.

Molecular cloning and functional expression of bottle-nosed dolphin (Tursiops truncatus) interleukin-1 receptor antagonist

The bottle-nosed dolphin (Tursiops truncatus) interleukin-1 receptor antagonist IL-1ra cDNA was cloned from mitogen-stimulated peripheral blood mononuclear cells (PBMC) RNA utilizing the reverse transcription-polymerase chain reaction (RT-PCR). The sequence of this cDNA showed that dolphin IL-1ra clones contained open reading frames encoding 177 amino acids. Comparison of the deduced amino acids showed that dolphin IL-1ra sequence shared 87.6, 77.9, 77.4, 77.4, 76.4, and 75.8% similarity with the bovine, rabbit, equine, human, mouse, and rat IL-1ra sequences, respectively. Recombinant glutathione S-transferase (GST) dolphin IL-1ra produced in Escherichia coli (E. coli) was purified. This protein suppressed the cytostatic activity of dolphin IL-1beta on A375S2 cells, indicating that the dolphin IL-1ra cDNA obtained in the present study encodes biologically active dolphin IL-1ra.

Determination of the cDNA sequence and mRNA expression of interleukin-1 receptor antagonist in horses

OBJECTIVE

To determine the complementary DNA (cDNA) sequence of interleukin-1 receptor antagonist (IL-1ra) in horses and compare messenger RNA (mRNA) expression of IL-1ra among horses of various breeds.

SAMPLE POPULATION

Blood samples from neonatal and adult horses examined for a variety of diseases.

PROCEDURE

A polymerase chain reaction procedure was used to amplify a 220 base pair (bp) portion of the genomic DNA. The upstream and downstream regions of the cDNA sequence were determined by means of 5' and 3' rapid amplification of cDNA ends (RACE) procedures. Northern blot hybridization was used to examine steady-state mRNA expression of IL-1ra.

RESULTS

The consensus sequence of the cDNA obtained with the 5'-RACE procedure and the sequence for the 220 bp portion of the genomic DNA represented the putative sequence for secreted IL-1ra. The predicted secreted IL-1ra amino acid sequence contained 176 residues with an in-frame stop codon; the N-terminal 25 amino acid residues resembled the signal peptide reported for human secreted IL-1ra. An approximately 1.3 kilobase pair (kb) band that represented a portion of the 3' end of the coding region and the 3' untranslated region was obtained by use of the 3' -RACE procedure. Northern blot hybridization detected a 1.6 kb transcript in blood RNA from adult Arabian, Belgian, Thoroughbred, and Standardbred horses.

CONCLUSIONS

Results suggest that the DNA for equine secreted IL-1ra has a short (29 bp) 5' untranslated region, a 534 bp coding region, and a long (approximately 1,080 bp) untranslated region.

Equine T-cell cytokines. Protection and pathology

The ultimate reason for better characterizing the immune response to infectious agents is the hope that this knowledge may lead to the development of better preventative or therapeutic measures. As more information becomes available, it becomes possible to incorporate these findings into the design of better vaccines and treatments. Likewise, attempts to either enhance or suppress specific helper T-cell responses may be required to control immunopathologic reactions. Although cytokine intervention in the clinical setting remains theoretic at this time, future manipulation based on the TH1/TH2 paradigm is probable.

Gene therapy in veterinary medicine

Gene therapy in simple terms is the introduction of a gene into a cell, in vivo, in order to ameliorate a disease process. Human clinical trials have focused on the correction of monogenic deficiency diseases, cancer and AIDS. This paper summarises the technology of gene therapy, gives a brief synopsis of the current applications of gene therapy to veterinary medicine and discusses some of the problems which need to be overcome so that gene therapy can become accepted clinical practice.

Enzymatic amplification and expression of bovine interleukin-1 receptor antagonist cDNA

cDNA generated from lipopolysaccharide-stimulated bovine peripheral blood mononuclear cells was used to amplify and clone the bovine interleukin-1 receptor antagonist (IL-1ra) using primers derived from semi-conserved regions between human and mouse IL-1ra sequences. 5' and 3' terminal sequences of bovine IL-1ra were amplified by 5' and 3' rapid amplification of cDNA ends. The deduced amino acid sequence of bovine IL-1ra demonstrated 80%, 78%, 78%, 77% and 76% homology with human, mouse, rat, rabbit and equine sequences, respectively. Recombinant bovine IL-1ra produced in Escherichia coli suppressed the growth inhibitory activity of bovine IL-1beta on A375 cells in a dose-dependent manner, indicating that the present bovine IL-1ra cDNA encodes biologically active proteins.