Inflammation in horses

Changes in the Secretion of Anti-Inflammatory Cytokines and Acute-Phase Proteins in the Uterus after Artificial Insemination in the Mare

Simple Summary

Semen deposition into the uterus during mating or artificial insemination induces a rapid inflammatory response, and, in susceptible mares, persistent endometritis can develop. Cytokines are mediators involved in the regulation of the inflammatory process, and acute phase proteins are the most sensitive indicators of the inflammatory process. Therefore, the aim of this research was to determine the secretion of anti-inflammatory cytokines and acute-phase proteins in the uterus before and after artificial insemination in the mare. The obtained results indicate that the status of the mare before artificial insemination has little effect on the response measured shortly after artificial insemination. The presence of intrauterine fluid during estrus is not connected with the inflammation parameters investigated in this study at 7 h post artificial insemination. Detailed examination of the mare’s reproductive tract before and after artificial insemination guarantees high fertility.

Abstract

The objective of the study was to evaluate the concentrations of interleukin-1 receptor antagonist (IL-1RA), interleukin-10 (IL-10), serum amyloid A (SAA) and haptoglobin (Hp) in uterine lavage fluid before and after artificial insemination (AI). Based on ultrasound examination, mares were divided into: Group 1 (n = 9), no fluid was detected in the uterus during estrus and 7 h after AI; Group 2 (n = 8), no fluid was detected in the uterus during estrus but 7 h after AI fluid was detected in the uterus; Group 3 (n = 8), fluid was detected in the uterus during estrus and also 7 h after AI. In all groups of mares, a significant increase in polymorphonuclear cells (PMN) and a significant increase in IL-1RA and SAA were recorded 7 h after AI. The obtained results show that, regardless of the status of the mare before AI, the endometrial response characterized by PMN influx, and SAA, Hp, IL-1RA and IL-10 production, is similar. The presence of intrauterine fluid during estrus is not connected with PMN influx but can impact uterine IL-1RA production at this time.

Protective Effect of Silibinin on Lipopolysaccharide-Induced Inflammatory Responses in Equine Peripheral Blood Mononuclear Cells, an In Vitro Study

Simple Summary

Natural compounds are often an important source of biologically active molecules, which can find important applications in the treatment or pharmacological prevention of several pathologies. Silibinin is a natural polyphenolic flavonoid that is extracted from plant milk thistle, Silybum marianum. Silibinin has been reported to have antioxidant and immunomodulatory and anti-inflammatory activities. In horses, in particular, inflammation secondary to bacterial infection or translocation is one of the most frequent causes of morbidity and mortality. The aim of this study was to test the effect of silibinin on lipopolysaccharide (LPS)-induced inflammatory response in equine peripheral blood mononuclear cells (PBMCs). Taken together, our results showed an interesting prospective in therapeutic use of silibinin in equine inflammatory disease. Furthermore, the results from this study support the evidence of use equine PBMCs as an in vitro model to study inflammatory and immune response and for drug screening into the target specie.

Abstract

Although inflammation is an important physiological response, it plays a prominent role in several diseases across the mammalian species. In horses, in particular, inflammation secondary to bacterial infection or translocation is one of the most frequent causes of morbidity and mortality. Research in new molecules with anti-inflammatory and immunomodulatory proprieties and safe use profile is constantly an active field; natural compounds are an important source of molecules with peculiar properties such as antioxidants, anti-inflammatory and immune modulating. Silibinin, a natural polyphenolic flavonoid, extracted from plant milk thistle, Silybum marianum, has been reported to have actions such as antioxidant immunomodulatory and anti-inflammatory. The aim of this study was to test the effect of silibinin on lipopolysaccharide (LPS)-induced inflammatory response in equine peripheral blood mononuclear cells (PBMCs). Our results showed the protective effect of silibinin 10 μM and 50 μM in equine PBMCs stimulated with LPS. Silibilinin was able to prevent the LPS induced increased levels of TNF-α, IL-1β, IL-6 and IL-8. The results from this study on LPS-stimulated equine PBMCs showed that silibinin could be a useful pharmacological approach in treatment or prevention of several inflammatory conditions in horse.

Changes in blood biomarkers in Arabian horses with Clostridium difficile-induced enterocolitis

Clostridium difficile (CD) is considered a major health care problem both in developing and developed countries; frequently reported to be associated with enterocolitis and diarrhea in horses and other animals. In this study, we examined acute phase response (APR), cytokines response, neopterin (NP) procalcitonin (PCT) production and oxidative stress condition in horses and foals with C. difficile-induced enterocolitis (CDIE) and evaluated the effectiveness of these parameters as biomarkers for the disease. A total of 407 Arabian horses in 35 stables were examined between January 2017 to December 2018. Only 24 out of 407 horses showed two or more signs of CDIE. The blood level of serum amyloid A (SAA), haptoglobin (HP), proinflammatory cytokines (TNF-α, IL-6 and IL1-β), serum malondialdehyde (MDA), PCT and NPT in horses with CDIE were higher than in healthy horses. Nevertheless, the levels of nitric oxide (NO), superoxide dismutase (SOD) and total antioxidant concentration (TAC) were considerably lower in diseased horses compared to those that were healthy. The ROC curves for eleven selected blood parameters, both in healthy horses and horses with CDIE demonstrated that all examined blood markers had significant levels of differentiation between CDIE cases and healthy controls (AUC > 87.5). The data in this study suggest that the evaluation of acute-phase proteins, cytokines, PCT, NPT, and oxidative stress biomarkers may well be used as a tool for diagnosis and assessment of CDIE and in disease pathogenesis in Arabian horses.

A Comparative Review of Equine SIRS, Sepsis, and Neutrophils

The most recent definition of sepsis in human medicine can be summarized as organ dysfunction caused by a dysregulated host response to infection. In equine medicine, although no consensus definition is available, sepsis is commonly described as a dysregulated host systemic inflammatory response to infection. Defense against host infection is the primary role of innate immune cells known as neutrophils. Neutrophils also contribute to host injury during sepsis, making them important potential targets for sepsis prevention, diagnosis, and treatment. This review will present both historical and updated perspectives on the systemic inflammatory response (SIRS) and sepsis; it will also discuss the impact of sepsis on neutrophils, and the impact of neutrophils during sepsis. Future identification of clinically relevant sepsis diagnosis and therapy depends on a more thorough understanding of disease pathogenesis across species. To gain this understanding, there is a critical need for research that utilizes a clearly defined, and consistently applied, classification system for patients diagnosed with, and at risk of developing, sepsis.

Modulation of TNF-α, IL-1Ra and IFN-γ in equine whole blood culture by glucocorticoids

Glucocorticoids are important drugs in the treatment of many inflammatory, autoimmune and allergic diseases in humans and animals. We investigated the effects of hydrocortisone and dexamethasone on TNF-α, IL-1Ra and INF-γ release in stimulated whole blood cell culture from healthy horses. Whole blood cell cultures proved to be useful for the characterization of the anti-inflammatory properties of new drugs. Diluted equine whole blood was exposed to lipopolysaccharide (LPS) and PCPwL (a cocktail consisting of phythemagglutinin E, concanavalin A, pokeweed mitogen and lipopolysaccharide) in the presence or absence of hydrocortisone and dexamethasone (10^-12 - 10^-5 M). TNF-α and IL-1Ra (LPS) as well as IFN-γ (PCPwL) levels were measured in the supernatants using specific enzyme-linked immunosorbent assay (ELISA). The LPS-induced TNF-α and IL-1Ra as well as the PCPwL-induced IFN-γ levels were more potently suppressed by dexamethasone than by hydrocortisone in a concentration-dependent manner. Dexamethasone inhibited TNF-α, IL-1Ra and IFN-γ with the half maximal inhibition concentration (IC₅₀) values of 0.09 μM, 0.453 μM and 0.001 μM, respectively, whereas hydrocortisone inhibited these cytokines with lower IC₅₀ values of 1.45 μM, 2.96 μM and 0.09 μM, respectively. Our results suggest that the equine whole blood test system is useful and reliable to evaluate drug effects and immunological alterations and offers several advantages including simple and cheap performance in physiological and pathological conditions.

Release kinetics of tumor necrosis factor-α and interleukin-1 receptor antagonist in the equine whole blood

Background

Horses are much predisposed and susceptible to excessive and acute inflammatory responses that cause the recruitment and stimulation of polymorphnuclear granulocytes (PMN) together with peripheral blood mononuclear cells (PBMC) and the release of cytokines. The aim of the study is to develop easy, quick, cheap and reproducible methods for measuring tumor necrosis factor alpha (TNF-α) and interleukin-1 receptor antagonist (IL-1Ra) in the equine whole blood cultures ex-vivo time- and concentration-dependently.

Results

Horse whole blood diluted to 10, 20 and 50 % was stimulated with lipopolysaccharide (LPS), PCPwL (a combination of phytohemagglutinin E, concanavalin A and pokeweed mitogen) or equine recombinant TNF-α (erTNF-α). TNF-α and IL-1Ra were analyzed in culture supernatants, which were collected at different time points using specific enzyme-linked immunosorbent assays (ELISA). Both cytokines could be detected optimal in stimulated 20 % whole blood cultures. TNF-α and IL-1Ra releases were time-dependent but the kinetic was different between them. PCPwL-induced TNF-α and IL-1Ra release was enhanced continuously over 24–48 h, respectively. Similarly, LPS-stimulated TNF-α was at maximum at time points between 8–12 h and started to decrease thereafter, whereas IL-1Ra peaked later between 12–24 h and rather continued to accumulate over 48 h. The equine recombinant TNF-α could induce also the IL-1Ra release.

Conclusions

Our results demonstrate that similar to PCPwL, LPS stimulated TNF-α and IL-1Ra production time-dependently in whole blood cultures, suggesting the suitability of whole blood cultures to assess the release of a variety of cytokines in health and diseases of horse.

Immune response of healthy horses to DNA constructs formulated with a cationic lipid transfection reagent

Background

Deoxyribonucleic acid (DNA) vaccines are used for experimental immunotherapy of equine melanoma. The injection of complexed linear DNA encoding interleukin (IL)-12/IL-18 induced partial tumour remission in a clinical study including 27 grey horses. To date, the detailed mechanism of the anti-tumour effect of this treatment is unknown.

Results

In the present study, the clinical and cellular responses of 24 healthy horses were monitored over 72 h after simultaneous intradermal and intramuscular application of equine IL-12/IL-18 DNA (complexed with a transfection reagent) or comparative substances (transfection reagent only, nonsense DNA, nonsense DNA depleted of CG).

Although the strongest effect was observed in horses treated with expressing DNA, horses in all groups treated with DNA showed systemic responses. In these horses treated with DNA, rectal temperatures were elevated after treatment and serum amyloid A increased. Total leukocyte and neutrophil counts increased, while lymphocyte numbers decreased. The secretion of tumour necrosis factor alpha (TNFα) and interferon gamma (IFNγ) from peripheral mononuclear blood cells ex vivo increased after treatments with DNA, while IL-10 secretion decreased. Horses treated with DNA had significantly higher myeloid cell numbers and chemokine (C-X-C motif) ligand (CXCL)-10 expression in skin samples at the intradermal injection sites compared to horses treated with transfection reagent only, suggesting an inflammatory response to DNA treatment.

In horses treated with expressing DNA, however, local CXCL-10 expression was highest and immunohistochemistry revealed more intradermal IL-12-positive cells when compared to the other treatment groups.

In contrast to non-grey horses, grey horses showed fewer effects of DNA treatments on blood lymphocyte counts, TNFα secretion and myeloid cell infiltration in the dermis.

Conclusion

Treatment with complexed linear DNA constructs induced an inflammatory response independent of the coding sequence and of CG motif content. Expressing IL-12/IL-18 DNA locally induces expression of the downstream mediator CXCL-10.

The grey horses included appeared to display an attenuated immune response to DNA treatment, although grey horses bearing melanoma responded to this treatment with moderate tumour remission in a preceding study. Whether the different immunological reactivity compared to other horses may contributes to the melanoma susceptibility of grey horses remains to be elucidated.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0452-3) contains supplementary material, which is available to authorized users.

Influence of the uterine inflammatory response after insemination with frozen-thawed semen on serum concentrations of acute phase proteins in mares

The aim of this study was to investigate the clinical relevance of measuring blood concentrations of serum amyloid A (SAA), haptoglobin (Hp) and fibrinogen (Fib) in horse reproductive management, and changes in response to artificial insemination (AI) with frozen-thawed semen. Standardbred mares (n=18) with different reproductive status (eight healthy mares in first postpartum oestrus, five healthy barren mares and five mares with endometritis) were inseminated with frozen-thawed semen. Endometritis was evaluated during oestrus by bacteriological culture, cytology and presence of ultrasonically visible intrauterine fluid during oestrus. Concentrations of SAA, Hp and Fib were analysed in the blood in every 48h during oestrus and until 5, 6 or 7 days after AI. The day of sampling and number of blood samples varied between mares because of length of the oestrus and time of AI. Changes in concentrations of SAA, Hp and Fib were evaluated based on the day of sampling regard to AI and classification of the mares. There were no differences in SAA, Hp and Fib concentrations over time before or after AI or between the groups of mares. The insemination of mares with frozen-thawed semen did not increase the plasma concentrations of SAA, Hp and Fib above clinical threshold concentration and there were no differences between susceptible or healthy mares.

Expression of interleukin-1β, interleukin-8, and interferon-γ in blood samples obtained from healthy and sick neonatal foals

OBJECTIVE

To evaluate and compare the gene expression of interleukin(IL)-1β, IL-8, and interferon-γ during the first 72 hours after birth in healthy foals and during the first 72 hours after hospitalization in sick neonatal foals and investigate correlations of clinicopathologic variables with cytokine expressions in healthy and sick neonatal foals.

ANIMALS

33 foals < 7 days old (10 healthy foals, 7 foals with sepsis, 6 foals with peripartum asphyxia syndrome, and 12 foals with other diseases [2 with failure of passive transfer of immunity only were not further evaluated]).

PROCEDURES

A blood sample (15 mL) was collected from each foal immediately after birth or hospital admission (0 hours) and at 24 and 72 hours later. Clinicopathologic variables were evaluated, and cytokine gene expression in WBCs was measured with an absolute quantitative real-time reverse transcriptase PCR assay.

RESULTS

At all time points, gene expression of interferon-γ was low in all groups. No time-dependent changes in cytokine expressions were detected in healthy or sick foals. Foals with sepsis had significantly higher IL-1β gene expression than did healthy foals, foals with peripartum asphyxia syndrome, or foals with other diseases. At 0 hours, IL-1β expression was correlated with plasma fibrinogen concentration in healthy foals and with the neutrophil-to-lymphocyte ratio in foals with sepsis; IL-8 expression was correlated with monocyte count in foals with sepsis and with arterial pH, plasma fibrinogen concentration, and plasma lactate concentration in foals with peripartum asphyxia syndrome.

CONCLUSIONS AND CLINICAL RELEVANCE

Data have suggested that evaluation of IL-1β expression in sick neonatal foals could help identify those with sepsis.

Immune parameters in mares resistant and susceptible to persistent post-breeding endometritis: Effects of immunomodulation

Our objective was to characterize immune parameters in susceptible (SM) and resistant (RM) mares, with and without artificial insemination (AI) and immunomodulation. Eight RM and eight SM were selected based on their reproductive history and functional tests. Both groups of mares were evaluated during three consecutive cycles: Cycle 1, untreated cycle (control); Cycle 2, AI with dead semen; Cycle 3, AI with dead semen and immunomodulation. Endometrial biopsies were taken during the three cycles as follows: Cycle 1--at estrus, when follicles > or =35mm and at diestrus (7+/-1 days after ovulation); Cycle 2--at estrus 24h post-AI, and at diestrus; Cycle 3--at estrus 24h after treatment with a Mycobacterium phlei cell-wall extract (MCWE) and AI, and at diestrus. The mRNA transcription (mRNAT) of IL-8 and IL-10 were determined by real-time PCR. Image analysis of immunohistochemistry slides was performed using digital software (Image-Pro Plus v 5.0; Media Cybernetics); the percentage of stained area was determined for Major Histocompatibility Complex II (MHC-II), polymorphonuclear leukocytes (PMN) and T lymphocytes (TL) on each tissue section. In Cycle 1, SM had significantly higher MHC-II, TL, PMN and IL-8 than RM during estrus (P<0.006, P<0.0005, P<0.05, respectively), while transcription of IL-10 was significantly lower than in RM (P<0.0001). During diestrus, SM had higher levels of TL, PMN and IL-8 than RM (P<0.0001). After AI (Cycle 2), SM had higher levels of IL-8 and lower levels of IL-10 than RM at estrus and no differences were detected for MHC-II, TL and PMN positive cells. During diestrus in the same cycle, all the immune parameters were higher in SM mares (P<0.005, P<0.0004, P<0.0001, P<0.02, respectively). When MCWE was applied at the time of AI (Cycle 3), SM expressed significant higher levels of IL-10 24h after treatment (P<0.005), which were also higher than in the control Cycle 2 or after AI (Cycle 2). However, no significant differences were detected for MHC-II, lymphocytes-PMN or IL-8 between SM and RM during diestrus in Cycle 3. This study showed that SM had higher levels of all immune parameters except IL-10 than RM during Cycle 1. After AI (Cycle 2), the inflammatory condition persisted in SM but not RM mares until day 7 post-ovulation. Following treatment with MCWE at the time of AI (Cycle 3) uterine immunological changes in SM resulted in an endometrial immune environment similar to that found in normal RM.

Equine neonatal sepsis

Neonatal infection remains a leading cause of morbidity and mortality in the equine industry, despite advances in prevention and treatment. Many factors can influence a foal's risk for the development of sepsis in the peripartum period. This article discusses those factors, causative organisms, and therapeutic options. Factors that influence prognosis and potential preventative strategies also are addressed.

Endometrial IL-1β, IL-6 and TNF-α, mRNA expression in mares resistant or susceptible to post-breeding endometritis

Endometrial mRNA expression of the pro-inflammatory cytokines interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) was assessed in mares resistant (RM) or susceptible (SM) to persistent post-breeding endometritis (PPBE). Eight RM and eight SM, were selected based on reproductive records and functional tests out of a herd of 2,000 light cross-type mares. Three experiments were done to study transcription patterns in (i) basal conditions; (ii) after artificial insemination (AI); and (iii) after administration of an immunomodulator at time of artificial insemination. Endometrial biopsies were taken during consecutive cycles: (i) at estrus, when follicles reached 35 mm and at diestrus (7 +/- 1 days after ovulation); (ii) at 24 h post-AI, with dead semen (estrus) and in diestrus; (iii) at 24 h after treatment with a Mycobacterium phlei cell-wall extract (MCWE) preparation and AI (with dead semen), and at diestrus. mRNA expression was quantitated by real time PCR. Under basal conditions, SM had significantly higher mRNA expression of all cytokines in estrus and of IL-1beta and TNF-alpha in diestrus, compared to RM. After AI, there were no differences between RM and SM in estrus; however, mRNA expression for all three pro-inflammatory cytokines was higher than under basal conditions. In diestrus, RM showed significantly lower IL-1beta and TNF-alpha mRNA expression than SM. When MCWE was administered at time of AI, no differences between cytokine induction from RM and SM were found. Globally, mRNA expression for all three cytokines correlated well among themselves when expression was high. The present study showed that (i) in basal conditions RM had lower mRNA expression of pro-inflammatory cytokines than SM with no effect of estrous cycle; (ii) AI upregulated mRNA expression for all three cytokines in both RM and SM, with persistance in diestrus in the latter; (iii) treatment with MCWE at time of AI down-regulated mRNA expression of IL-1 with significant effects in SM which behaved like RM. Immunomodulation with MCWE could be of help in restoring homeostatic local inflammatory mechanisms, thus assisting in the prophylaxis of post-breeding endometritis in mares.

Characterization of equine E-selectin

Expression of E-selectin on activated endothelium is a critical initial step that leads to extravasation of leucocytes during inflammation, yet E-selectin is largely uncharacterized in several animal species including the horse. We have sequenced and compared E-selectin genes derived from activated cultures of purified equine (horse), cervid (black-tailed deer) and ovine (sheep) pulmonary artery endothelial cells (ECs). Phylogenetic and amino acid sequence comparisons indicate that bovine, cervid and ovine E-selectin are similar, whereas human and equine E-selectin are more closely related to each other than to the ruminant molecules. Human E- and P-selectin-specific monoclonal antibodies that also recognize equine E-selectin were identified and used to characterize its expression. Expression of E-selectin was more readily induced by lipopolysaccharide treatment in equine ECs than in human ECs and supported adhesion and activation of neutrophils, consistent with the extreme sensitivity of horses to endotoxaemia and septic shock.