Clinical, Hematological, and Biochemical Analysis of Experimental Endotoxemia in Thoroughbred Horses

Expression of tlr4, md2 and cd14 in equine blood leukocytes during endotoxin infusion and in intestinal tissues from healthy horses

The expression of tlr4, md2 and cd14 was studied in equine blood leukocytes and in intestinal samples using real time PCR. The stability of three commonly used reference genes, glyceraldehyde-3P-dehydrogenase (GAPDH), hypoxantine ribosyltransferase (HPRT) and succinate dehydrogenase complex subunit A (SDHA), was evaluated using qbase(PLUS). The equine peripheral blood mononuclear cells (eqPBMC) examined were either stimulated in vitro with Phorbol 12-myristate 13-acetate (PMA) and ionomycin or with the CpG oligodeoxynuclotide 2216 (CpG-ODN 2216) or obtained from horses before, during and after infusion of endotoxin. Intestinal tissue from healthy horses was sampled at ileum, right dorsal colon and rectum. Ranking of the three reference genes used for normalisation identified the combination HPRT/SDHA as most suitable both when determined ex vivo in leukocytes obtained from experimentally induced endotoxaemia and in eqPBMC activated in vitro while HPRT/GAPDH were most appropriate for the intestinal samples. The relative amounts of mRNA for TLR4 and MD-2 increased threefold during in vitro activation of the cells with CpG-ODN 2216 but was decreased in cultures stimulated with PMA/ionomycin. A transient elevation in the transcription of tlr4 and md2 was also evident for equine blood leukocytes following endotoxaemia. The levels of mRNA for CD14 on the other hand remained unaffected both during the induction of endotoxaemia and in the in vitro stimulated PBMCs. A low steady expression of TLR4, MD-2 and CD14 mRNA was demonstrated for the intestinal samples with no variation between the intestinal segments analysed. Thus, the foundation for real time PCR based levels of analysis of mRNA for all three components in the equine LPS receptor complex in different intestinal segments was set, making it possible to carry out future expression studies on clinical material.

Clinical evaluation of serum alcohol dehydrogenase activity in horses with acute intestinal obstruction

OBJECTIVES

To measure serum alcohol dehydrogenase (ADH) activity in horses with acute intestinal obstruction and to determine the diagnostic and prognostic utility of this analyte.

DESIGN

Prospective observational study.

SETTING

University Veterinary Hospital.

ANIMALS

Thirty healthy horses (control group) and 77 horses with acute intestinal obstruction, including 36 horses with nonstrangulating obstruction (23 with left ventral colon impaction and 13 with left dorsal displacement [G1], 22 with small intestinal strangulation [G2], and 19 with colon torsion [G3]).

INTERVENTIONS

Serum ADH activity was assayed spectrophotometerically in all horses. Serum lactate concentration and hepatic enzyme (aspartate aminotransferase, gamma-glutamyl transferase, glutamate dehydrogenase) activities were measured using an automatic analyzer.

MEASUREMENTS AND MAIN RESULTS

The median [interquartile range] serum ADH activity in healthy horses was 10.5 [8.7-11 U/L]. ADH activity was significantly increased (P<0.05) in G1=16.5 [13.8-18 U/L], G2=40 [20-74.9 U/L], and G3=63.2 [40-78 U/L] compared with healthy controls. Aspartate aminotransferase and glutamate dehydrogenase activities were also significantly increased in G3 in comparison with controls. ADH activity was correlated with serum lactate concentration in G1 and G3, respectively (P<0.01, r=0.55 and 0.8). Other liver enzymes did not show any significant correlation with lactate. ADH activity was directly related to the probability of strangulation; odds ratio=1.11. ADH activity >20 U/L had 80.6% specificity and 80.5% sensitivity for discriminating horses with strangulating obstruction. Twelve horses euthanized before surgery were excluded from the outcome analysis. Increasing ADH activity was associated with nonsurvival; odds ratio=1.03. ADH activity <80 U/L had 94.44% specificity and 66.67% sensitivity for survival.

CONCLUSION

Serum ADH activity may be a useful clinical parameter in detecting intestinal strangulation in horses and may provide some prognostic value in horses with acute intestinal obstruction.

Effect of recombinant interleukin-10 on some haematological and biochemical parameters in a rat endotoxaemic model

Recombinant interleukin-10 (rIL10) has been found to suppress the synthesis of tumour necrosis factor (TNF), interleukin-1 (IL-1), interleukin-6 (IL-6) and tissue factor and to improve survival from experimental sepsis. The aim of this study was to evaluate the protective effect of rIL-10 on lipopolysaccharide-(LPS-) induced haematological and biochemical disturbances in rats. In the present study, 40 rats were used and divided equally into four groups. Group 1 (control group, C) was treated with 0.9% saline. Group 2: LPS was injected intravenously (1.6 mg/100 g), Group 3 received rIL10 treatment (125 μg/kg) 2 min before 0.9% saline injection, Group 4 received rIL10 treatment 2 min before endotoxin treatment. When compared with the controls, platelet count, leukocyte count (with a marked neutrophilia and lymphopenia) and fibrinogen were decreased, while activated partial thromboplastin time (APTT) and prothrombin time (PT) were prolonged in the endotoxaemic rats. In addition, LPS caused statistically significant increases in plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities as well as creatinine, cholesterol and triglyceride concentrations, while it caused a statistically significant decrease in glucose, total protein and albumin levels as compared to the control group. On the other hand, rIL10 significantly suppressed disturbances in the haematological and biochemical parameters associated with endotoxaemia. As a result, rIL10 may be efficacious in preventing haematological disorders, tissue damage and changes in lipid, protein and carbohydrate metabolism in endotoxaemia.

Fibrin deposits and organ failure in newborn foals with severe septicemia

BACKGROUND

Septicemia in human neonates frequently is complicated by activation of the coagulation system, disseminated intravascular coagulation (DIC) and multiple organ failure syndrome, which may contribute to high mortality. In adult horses with DIC, the lung has been the organ most frequently affected by fibrin deposits. In addition, in vivo studies suggest that hemostatic mechanisms may be immature in foals < 1-day old.

HYPOTHESIS

Newborn foals with severe septicemia have fibrin deposits in their tissues independently of their age, and these fibrin deposits are associated with organ failure.

ANIMALS

Thirty-two septic and 4 nonseptic newborn foals euthanized for poor prognosis.

METHODS

Tissue samples (kidney, lung, and liver) collected on postmortem examination were stained with phosphotungstic acid hematoxylin (PTAH) and immunohistochemistry (IHC) for blind histologic examination. A fibrin score (grades 0-4) was established for each tissue sample and for each foal. Medical records were reviewed for assessing clinical evidence of organ failure during hospitalization.

RESULTS

Fibrin deposits were found in most septic foals (28/32 when using IHC and 21/32 when using PTAH), independently of the age of the foal. The lung was the most affected tissue (97% of the septic foals). Additionally, organ failure was diagnosed in 18/32 septic foals (8 with respiratory failure, 14 with renal failure), although a statistical association with severe fibrin deposition was not identified.

CONCLUSIONS AND CLINICAL IMPORTANCE

Nonsurviving septic foals have fibrin deposits in their tissues, a finding consistent with capillary microthrombosis and DIC.

Endotoxin-induced Injury of the Central, Autonomic and Enteric Nervous Systems and Intestinal Muscularis in Thoroughbred Horses

To evaluate the effects of endotoxin on the morphology of the equine central, autonomic and enteric nervous system and intestinal muscularis, six Thoroughbred horses with experimentally induced endotoxaemia were examined. The lesions in the central nervous system consisted of perivascular oedema around arterioles, suggesting brain oedema, and ring haemorrhages around veins, similar to those in human patients with septic shock. In the cranial mesenteric ganglia, neuronal cell bodies became pink or red, with shrinkage of cytoplasm indicative of ischaemic changes; intramural and perivascular infiltration by erythrocytes and neutrophils occurred around arterioles in the epineurium (acute focal interstitial inflammation). In addition, transmission electron microscopy revealed oedema of the endoneurium and mesoaxon in the nerve fascicles running inside or outside the ganglia. Myenteric neurons showed shrinkage of the cytoplasm with multiple cytoplasmic vacuoles, suggesting ischaemic changes. Oedematous degeneration and coagulation necrosis of smooth muscle cells, with dissociation of the cells, were prominent in the tunica muscularis. It is suggested that arterionecrosis elicited by endotoxin and frequently observed in the autonomic and enteric nervous system and intestinal muscularis, was the result of vasoconstriction or vasospasm.

Mesenteric Arterionecrosis in Natural and Experimental Equine Endotoxaemia

To test the hypothesis that mesenteric arterionecrosis (MA) occurs in horses with naturally occurring endotoxaemia (ET) and in those with experimentally induced ET, the mesentery and gastrointestinal tract of 21 Thoroughbred racehorses (15 with spontaneous colic suspected to be due to ET, and six with experimentally induced ET) were examined. MA, which occurred in 13 of the 15 horses with spontaneous colic and in all six of the cases of experimental ET, was morphologically similar in the two groups of animals. This suggested that the pathogenesis of the MA was fundamentally similar in the two groups, and that MA is a pathognomonic feature of equine ET. In addition to histolysis of the arterial walls associated with infiltration of blood components, changes were noted in the medial smooth muscle including formation of many intracellular vacuoles within single smooth muscle cells, cytoplasmolysis, necrosis with granules and vacuoles, and coagulation necrosis; similar changes have been observed in cases of prolonged angiospasm or vasoconstriction. It is suggested that the effects of sustained arterial contraction leading to intimal and medial damage influence the pathomorphogenesis of MA.

Arterionecrosis of the Equine Mesentery in Naturally Occurring Endotoxaemia

This report describes the mesenteric arteriolar lesions in a Thoroughbred racehorse with endotoxaemia due to colic. The vascular lesions consisted of a striking loss of medial smooth muscle cells, associated with granular cell debris derived from necrosed muscle cells, plasma insudation, erythrocyte infiltration and the deposition of a fibrinoid substance (fibrinoid degeneration) in the entire arterial wall, possibly produced by the infiltration of blood components through endothelial cell junctions into the arterial wall. The morphology of the mesenteric arteriolar necrosis closely resembled that seen in experimental equine endotoxaemia and in horses that died from colic; it also resembled that of Shiga toxin-induced arteriolar lesions in oedema disease of swine and of the arterionecrosis in human cerebral arteries that may lead to hypertensive intracerebral haemorrhage.