Effects of equine metabolic syndrome on inflammation and acute-phase markers in horses

Arthrospira platensis enriched with Cr(III), Mg(II), and Mn(II) ions improves insulin sensitivity and reduces systemic inflammation in equine metabolic affected horses

Equine metabolic syndrome (EMS) is a critical endocrine condition in horses, characterized by hyperinsulinemia, hyperlipidemia, and insulin resistance, posing a significant threat to their health. This study investigates the efficacy of supplementing EMS-affected horses with Arthrospira platensis enriched with Cr(III), Mg(II), and Mn(II) ions using biosorption process in improving insulin sensitivity and glucose tolerance, reducing inflammation, and mitigating obesity-related fat accumulation. Our results demonstrate that Arthrospira supplementation reduces baseline insulin and glucose levels, contributing to decreased adipose tissue inflammation. Furthermore, Arthrospira supplementation results in a decrease in body weight and improvements in overall body condition scores and cresty neck scores. Additionally, administration of Arthrospira leads to reduced levels of triglycerides and aspartate aminotransferase, indicating a decrease in hepatic adiposity and inflammation. These findings suggest that Arthrospira, enriched with essential micro- and macroelements, can be an advanced feed additive to enhance insulin sensitivity, promote weight reduction, and alleviate inflammatory processes, thereby improving the overall condition of horses affected by EMS. The use of Arthrospira as a feed additive has the potential to complement conventional management strategies for EMS.

Epidemiological investigation of insulin dysregulation in Shetland and Welsh ponies in Australia

BACKGROUND

Insulin dysregulation (ID) is central to equine metabolic syndrome. There are limited epidemiological studies investigating dynamic testing of ID in ponies.

OBJECTIVES

To evaluate prevalence and risk factors for ID through dynamic testing of hyperinsulinaemia (DHI) and insulin resistance (IR).

STUDY DESIGN

Cross-sectional.

METHODS

Sex, age, breed, height, cresty neck score (CNS), body condition score (BCS), laminitis, HMGA2:c.83G>A genotype and pituitary pars intermedia dysfunction (PPID) status were documented. Dynamic hyperinsulinaemia was diagnosed with an oral sugar test (OST) and IR with an insulin tolerance test (ITT). Owners completed surveys reporting activity, laminitis history and perception of body condition using a (1-9) visual analogue scale (VASo). Ordinal scores were converted to binary outcomes for CNS (≤2/5 or ≥3/5), BCS and VASo (≤6/9 or ≥7/9). Variables associated with insulin concentrations, glucose reduction after the ITT and laminitis were evaluated with mixed effects regression models accounting for random effects of farms.

RESULTS

Among 167 ponies tested, median (range) age was 9 (4-21) years and BCS was 6 (4-8). Prevalence (95% confidence interval [CI]) of ID was 61 (53-68)%. Factors associated with insulin concentrations (estimate [95% CI]; μIU/mL) 60 min post-OST were: age (1.07 [1.02-1.11]), CNS (≥3/5, 1.52 [1.04-2.23]) and VASo (≥7/9, 1.75 [1.09-2.79]); and 90 min post-OST were: age (1.08 [1.03-1.12]), CNS (≥3/5, 1.80 [1.22-2.64]), VASo (≥7/9, 2.49 [1.52-4.08]) and sex (male, 0.64 [0.45-0.91]). Factors associated with glucose reduction after the ITT (estimate [95% CI]; %) were: age (-1.34 [-2.01 to -0.67]), sex (female, -6.21 [-11.68 to -0.74]) and VASo (≥7/9, -1.74 [-18.89 to -4.78]). Factors associated with laminitis (odds ratio [95% CI]) were DHI (4.60 [1.68-12.58]), IR (3.66 [1.26-10.61]) and PPID (11.75 [1.54-89.40]).

MAIN LIMITATIONS

Single time-point sampling, laminitis definition and diet analysis.

CONCLUSIONS

Ageing, being female and owner-perceived obesity were associated with ID.

Effect of Exercise Conditioning on Countering the Effects of Obesity and Insulin Resistance in Horses-A Review

Obesity is an important health concern in horses, along with humans and companion animals. Adipose tissue is an inflammatory organ that alters the insulin-signaling cascade, ultimately causing insulin dysregulation and impaired glucose metabolism. These disruptions can increase the risk of metabolic disease and laminitis in horses and may also impact energy metabolism during exercise. A single bout of exercise, along with chronic exercise conditioning, increases insulin sensitivity and glucose disposal via both contraction- and insulin-mediated glucose uptake pathways. Regular exercise also increases calorie expenditure, which can facilitate weight (as body fat) loss. This paper explores the metabolic pathways affected by adiposity, as well as discusses the impact of exercise on insulin metabolism in horses.

Insulin dysregulated horses metabolic responses to forage pellets

Hyperinsulinemia-associated laminitis (HAL) is the primary concern for insulin dysregulated (ID) equids and their insulin response to the consumption of oral, nonstructural carbohydrates (NSC) has been shown to be a risk predictor for HAL development. This randomized, crossover study's objective was to examine the insulinemic responses to 3 forage pellets (1 g/kg BW) (timothy hay, TH, 9.5 % CP & 10 % NSC DM; alfalfa hay, AH, 16.3 % CP & 9.8 % NSC DM; timothy-alfalfa hay; TAH, 17.2 % CP & 9.8 % NSC DM) along with a positive (dehulled oats; OG, 14.7 % CP & 59.7 % NSC DM) and negative dietary challenge control (low-NSC; LNSC, 12.8 % CP & 5.4 % NSC DM) of ID (n = 8; 16.1 ± 2.2 yr; 565.4 ± 99.1 kgs.) and non-ID (NID; n = 7; 17.0 ± 2.8 yr; 583.6 ± 57.9 kgs.) horses. ID horses had higher positive incremental area under the curve for insulin (IAUCi) (ID: 890 ± 925 µIU/mL*minute vs. NID: 225 ± 228 µIU/mL*minute), peak (ID: 101.5 ± 80.72 µIU/mL vs. NID: 25.7 ± 7.2 µIU/mL), and delta (ID: 45.5 ± 77.1 µIU/mL vs. NID: 4.9 ± 5.3 µIU/mL) insulin for all forage pellets compared to NID (p < 0.01). ID horses IAUCi for the forage pellets was not different compared to the LNSC (218 ± 327 µIU/mL*minute) but was different from OG (10,522 ± 4,565 µIU/mL*minute). ID horses' lack of an augmented insulinemic response to the low NSC forage pellets (fed in small amounts) indicates that they could be a safe feedstuff for ID animals.

Prolonged hyperinsulinemia increases the production of inflammatory cytokines in equine digital lamellae but not in striated muscle

Hyperinsulinemia is the key feature of equine metabolic syndrome (EMS) which leads to debilitating sequelae. Hyperinsulinemia-associated laminitis (HAL) is one of the major sequelae of EMS, although the pathophysiological mechanisms are not well elucidated. Using an equine model, we hypothesized that expression of inflammatory markers would be increased in digital lamellae and striated muscle following prolonged hyperinsulinemia. Healthy Standardbred horses (5.4 ± 1.9 years) were alternately assigned to a prolonged euglycemic-hyperinsulinemic clamp (pEHC) or control group (n = 4 per group). Following a 48 h pEHC or a 48 h infusion of a balanced electrolyte solution (controls), biopsies were collected from digital lamellar tissue, skeletal muscle and cardiac muscle were obtained. All hyperinsulinemic horses developed laminitis regardless of previous health status at enrollment. Protein expression was quantified via Western blotting. A significant (P < 0.05) upregulation of the protein expression of heat shock protein 90 (HSP90), alpha 2 macroglobulin (A2M) and fibrinogen (α, β isoforms), as well as inflammatory cytokines including interleukin-1β were detected in digital lamellae following prolonged hyperinsulinemia. In contrast, protein expression of cytokines and acute phase proteins in heart and skeletal muscle was unchanged following hyperinsulinemia. Upregulation of inflammatory cytokines and acute phase proteins in digital lamellae during prolonged hyperinsulinemia may reveal potential biomarkers and novel therapeutic targets for equine endocrinopathic laminitis. Further, the lack of increase of inflammatory proteins and acute phase proteins in striated muscle following prolonged hyperinsulinemia may highlight potential anti-inflammatory and cardioprotective mechanisms in these insulin-sensitive tissues.

Identifying possible thresholds for nonstructural carbohydrates in the insulin dysregulated horse

BACKGROUND

Identifying intake levels of nonstructural carbohydrates (NSCs) that limit the postprandial insulinaemic response in the insulin dysregulated (ID) horse may help reduce hyperinsulinaemia-associated laminitis (HAL) risk.

OBJECTIVE

To determine if ID horses have thresholds for pure sources of starch and sugar, above which there is an augmented insulin response.

STUDY DESIGN

Randomised crossover experiment.

METHODS

Fourteen adult horses (6 ID and 8 noninsulin dysregulated, NID; matched for bodyweight) were randomly fed eight dietary treatments. Dietary treatments were formulated using a base of low-nonstructural carbohydrate pellet (LNSC; 0.04 g of water-soluble carbohydrates (WSCs)/kg bwt and 0.01 g of starch/kg bwt), to which pure sugar (dextrose) or starch (50:50 mix of waxy-maize and oat starch powder) sources were titrated to create diets with increasing amounts of either WSC (0.06-0.17 g WSC/kg bwt), or starch (0.03-0.1 g starch/kg bwt). Horses were fed each dietary treatment at a rate of 1 g/kg bwt once over 12 weeks. Serial blood samples were collected pre- and up to 240 min postprandially. Insulin was determined via RIA and diet analytes were determined via wet chemistry. Statistical analysis was performed with a mixed effect model. Positive incremental area under the curve for insulin (IAUCi) was calculated for all horses and dietary treatments.

RESULTS

There was no significant effect of diet in NID horses but diets with NSC >0.1 g/kg bwt produced an augmented response in ID horses compared with the LNSC (p < 0.05). ID horses IAUCi were also significantly different to all NID IAUCi for diets with NSC >0.1 g/kg (p < 0.04). Apparent thresholds for sugar and starch addition varied.

CONCLUSIONS

Based on this study, using supplemental pure starch and sugar sources, ID horses seem to have an apparent threshold for NSC of around 0.1 g/kg bwt/meal, above which significantly increased insulin responses are seen compared with NID horses.

The PTP1B Inhibitor Trodusquemine (MSI-1436) Improves Glucose Uptake in Equine Metabolic Syndrome Affected Liver through Anti-Inflammatory and Antifibrotic Activity

Background

Hyperactivation of protein tyrosine phosphatase (PTP1B) has been associated with several metabolic malfunctions ranging from insulin resistance, metaflammation, lipotoxicity, and hyperglycaemia. Liver metabolism failure has been proposed as a core element in underlying endocrine disorders through persistent inflammation and highly fibrotic phenotype.

Methods

In this study, the outcomes of PTP1B inhibition using trodusquemine (MSI-1436) on key equine metabolic syndrome (EMS)-related alterations including inflammation, fibrosis, and glucose uptake have been analyzed in liver explants collected from EMS-affected horses using various analytical techniques, namely, flow cytometry, RT-qPCR, and Western blot.

Results

PTP1B inhibition using trodusquemine resulted in decreased proinflammatory cytokines (IL-1β, TNF-α, and IL-6) release from liver and PBMC affected by EMS and regulated expression of major proinflammatory microRNAs such as miR-802 and miR-211. Moreover, MSI-1436 enhanced the anti-inflammatory profile of livers by elevating the expression of IL-10 and IL-4 and activating CD4+CD25+Foxp3+ regulatory T cells in treated PBMC. Similarly, the inhibitor attenuated fibrogenic pathways in the liver by downregulating TGF-β/NOX1/4 axis and associated MMP-2/9 overactivation. Interestingly, PTP1B inhibition ameliorated the expression of TIMP-1 and Smad7, both important antifibrotic mediators. Furthermore, application of MSI-1436 was found to augment the abundance of glycosylated Glut-2, which subsequently expanded the glucose absorption in the EMS liver, probably due to an enhanced Glut-2 stability and half-life onto the plasma cell membranes.

Conclusion

Taken together, the presented data suggest that the PTP1B inhibition strategy and the use of its specific inhibitor MSI-1436 represents a promising option for the improvement of liver tissue integrity and homeostasis in the course of EMS and adds more insights for ongoing clinical trials for human MetS management.

Age-Related Differences in Short-Term Transportation Stress Responses of Horses

Transportation of horses on short journeys can lead to an increase in stress. There are known age-associated changes in immune and metabolic responses in horses; however, no research exists evaluating how age may influence these responses to transportation stress. Eleven mares within two age groups, aged (n = 5, 22 ± 1 year) or young (n = 6, 2 ± 1 year), were transported 1 hour and 20 minutes. Peripheral blood and saliva were collected before and after transportation at baseline (2 to 3 weeks prior to transportation), 24 hours pre-transport, 1 hour before loading, 15 minutes, 30 minutes, 1 to 3 hours, 24 hours and 8 days post-transport. Heart rates, rectal temperatures, under the tail temperatures, serum cortisol, plasma ACTH, serum insulin, salivary cortisol and salivary IL-6 were measured. Whole blood gene expression of the cytokines IL-1b, IL-2, IL-6, IL-10, IFNγ, and TNFα were determined through qPCR, and peripheral blood mononuclear cells were isolated, stimulated, and stained to determine IFNγ and TNFα production. Serum cortisol (P < .0001), salivary cortisol (P < .0001) and heart rate (P = .0002) increased in response to transportation with no age differences. Rectal (P = .03) and under the tail temperatures (P = .02) were increased in young versus aged horses. ACTH was higher in aged horses (P = .007) and post-transportation (P = .0001). Aged horses showed a greater increase in insulin compared with young horses (P < .0001). While age does not seem to impact cortisol responses to short-term transportation in horses, it did influence the post transportation insulin response to stress in aged horses.

Association of the severity of colic in horses with oxidative stress biomarkers, acute-phase proteins, and certain trace elements

Sixty-one horses were enrolled in this study and divided into 3 different groups according to their severity of colic (heart rate, oral mucous membrane color, and abdominal distention): a strangulating colic (SC) group (n=21), non-strangulating colic (NC) group (n=20), and control group (n=20) consisting of randomly selected normal horses without signs of colic. The serum concentrations of haptoglobin, tumor necrosis factor-α (TNFα), nitric oxide (NO), malondialdehyde (MDA), zinc, iron, and copper were evaluated in all horses. The average concentration of TNFα in the SC group was higher than that in the control group (P<0.001). The TNFα concentration was higher in the NC group compared with the control group (P<0.001). Furthermore, the average concentration of TNFα tended to be higher in the SC group compared with the NC group (P=0.052). The average concentration of haptoglobin in the SC group was higher than that in the control group (P<0.001). The average concentration of NO was higher in the SC group compared with the NC group. (P=0.016) The average concentration of MDA was higher in the SC group compared with the control group (P=0.042). Furthermore, the concentration of MDA was higher in the SC group compared with the NC group (P=0.048). TNFα in horses with signs of colic may be a reliable indicator of prognosis and the severity of clinical signs. The haptoglobin concentration may be a useful marker in cases where animals are referred to clinicians a few days after the onset of colic. The concentrations of MDA and NO should be interpreted with caution.

Serum C-reactive Protein and Protein Electrophoretic Pattern Correlated With Age in Horses

Inflammaging or chronic, low-grade inflammation is a phenomenon characterizing age-related pathologies and natural processes in aging tissues. This study aimed to investigate the effect of age on the serum levels of C-reactive protein and protein electrophoretic pattern in horses. Thirty Italian Saddle horses from the same horse training center, were enrolled and divided in three equal groups according to their age: Group A (2-4 years), Group B (7-10 years), Group C (15-20 years). Blood samples were collected from each horse to evaluate hematological parameters and the serum concentration of C-reactive protein (CRP), total proteins, albumin, α1-, α-2, β1-, β2- and γ-globulins. One-way analysis of variance showed an age-related difference in the concentration of CRP, α1- and α2-globulins (P < 0.001) which increased with aging. Albumin and albumin:globulin ratio showed lower values in Groups B and C than Group A (P < 0.001). Age of horses showed a negative correlation with the values of albumin, and a positive correlation with CRP, α1- and α2-globulins concentration. The results of the current study suggest an increased acute phase response in adult and old horses compared to young ones. As α-globulin fractions include many other acute phase proteins (APPs) in addition to CRP, further studies to assess what other APPs could be involved in chronic inflammation or "inflammaging" are recommended in horse in order to improve knowledge on the key inflammatory biomarkers during aging in this species.

Impacts of Adiposity on Exercise Performance in Horses

There is ample research describing the increased risk of health concerns associated with equine obesity, including insulin dysregulation and laminitis. For athletes, the negative effect of weight carriage is well documented in racing thoroughbreds (i.e., handicapping with weight) and rider weight has been shown to impact the workload of ridden horses and to some degree their gait and movement. In many groups of competitive and athletic horses and ponies, obesity is still relatively common. Therefore, these animals not only are at risk of metabolic disease, but also must perform at a higher workload due to the weight of their adipose tissue. Excess body weight has been documented to affect gait quality, cause heat stress and is expected to hasten the incidence of arthritis development. Meanwhile, many equine event judges appear to favor the look of adiposity in competitive animals. This potentially rewards horses and ponies that are at higher risk of disease and reinforces the owner's decisions to keep their animals fat. This is a welfare concern for these animals and is of grave concern for the equine industry.

A one-health approach to identifying and mitigating the impact of endocrine disorders on human and equine athletes

Endocrinopathies affect multiple species in ever-increasing percentages of their populations, creating an opportunity to apply one-health approaches to determining creative preventative measures and therapies in athletes. Obesity and alterations in insulin and glucose dynamics are medical concerns that play a role in whole-body health and homeostasis in both horses and humans. The role and impact of endocrine disorders on the musculoskeletal, cardiovascular, and reproductive systems are of particular interest to the athlete. Elucidation of both physiologic and pathophysiologic mechanisms involved in disease processes, starting in utero, is important for development of prevention and treatment strategies for the health and well-being of all species. This review focuses on the unrecognized effects of endocrine disorders associated with the origins of metabolic disease; inflammation at the intersection of endocrine disease and related diseases in the musculoskeletal, cardiovascular, and reproductive systems; novel interventions; and diagnostics that are informed via multiomic and one-health approaches. Readers interested in further details on specific equine performance conditions associated with endocrine disease are invited to read the companion Currents in One Health by Manfredi et al, JAVMA, February 2023.

Gastro-Intestinal Microbiota in Equines and Its Role in Health and Disease: The Black Box Opens

Horses are large non-ruminant herbivores and rely on microbial fermentation for energy, with more than half of their maintenance energy requirement coming from microbial fermentation occurring in their enlarged caecum and colon. To achieve that, the gastro-intestinal tract (GIT) of horses harbors a broad range of various microorganisms, differing in each GIT segment, which are essential for efficient utilization of feed, especially to use nutrients that are not or little degraded by endogenous enzymes. In addition, like in other animal species, the GIT microbiota is in permanent interplay with the host's cells and is involved in a lot of functions among which inflammation, immune homeostasis, and energy metabolism. As for other animals and humans, the horse gut microbiome is sensitive to diet, especially consumption of starch, fiber, and fat. Age, breeds, stress during competitions, transportation, and exercise may also impact the microbiome. Because of its size and its complexity, the equine GIT microbiota is prone to perturbations caused by external or internal stressors that may result in digestive diseases like gastric ulcer, diarrhea, colic, or colitis, and that are thought to be linked with systemic diseases like laminitis, equine metabolic syndrome or obesity. Thus, in this review we aim at understanding the common core microbiome -in terms of structure and function- in each segment of the GIT, as well as identifying potential microbial biomarkers of health or disease which are crucial to anticipate putative perturbations, optimize global practices and develop adapted nutritional strategies and personalized nutrition.

Effect of aging on monocyte phagocytic and inflammatory functions, and on the ex vivo inflammatory responses to lipopolysaccharide, in horses

Studies investigating age-related changes in the function of monocytes are currently limited for horses. Thus, the main goal of this study was to determine the effect of aging on monocyte phagocytic capacity and pro-inflammatory cytokine responses to bacterial lipopolysaccharide (LPS). A second goal of this work was to examine the effect of aging on the inflammatory cytokine responses to LPS in a whole blood ex vivo model. Seven healthy young adult (4-6 years of age) and seven healthy senior horses (>20 years of age) were enrolled. Phagocytosis of E. coli, and pro-inflammatory cytokine (TNFα) responses to LPS, were measured in monocytes by flow cytometry. Gene expressions of pro-inflammatory cytokines (TNFα, IL-1β, IL-6, IL-8, IL-18, CCL-5, CCL-2) were measured in peripheral blood mononuclear cells (PBMCs) and whole blood by RT-qPCR post incubation for 2 h or 6 h with a low (0.01 µg/mL) or a high (1 µg/mL) dose of LPS. Two sets of statistical models were applied to compare the age groups, one adjusted, and one unadjusted for the horses' body condition scores (BCS). The percentage of monocytes that phagocytosed E. coli after 2 h of incubation was significantly lower in senior compared to young adult horses in the BCS-adjusted model. In the senior group, the expression of IL-1β in 2 h-0.01 µg/mL LPS-stimulated PBMCs was significantly higher than in the young adult group (BCS-adjusted and unadjusted models). In senior horses, expressions of IL-8 and IL-6 in whole blood samples stimulated for 6 h with 0.01 µg/mL LPS and for 2 h with 1 µg/mL LPS, respectively, were significantly lower than in young adult horses (BCS-adjusted models). The results of this study suggest that the phagocytic function of monocytes, as well as their IL-1β response to LPS may be altered in senior horses. In addition, the whole blood IL-8 and IL-6 gene expression responses to LPS may be insufficient in senior horses. While investigation of the effect of BCS on monocyte functions and whole blood pro-inflammatory LPS-responses was not a major goal of this work, it appears that adiposity may play a role in innate immune cell function, as significant differences between the age groups were often not apparent until the models were adjusted for BCS.

Can Procalcitonin Be Dosed in Bovine Milk Using a Commercial ELISA Kit?

Simple Summary

Mastitis is one of the major economic and animal welfare problems on dairy farms. The gold standard test for mastitis diagnosis is milk culture, but bacteria are not always isolated (only in 11–44% of milk samples from clinical cases of mastitis) and sometimes a positive culture can result from a contamination of the milk. Procalcitonin is a new biomarker which may lead to an early detection of inflammation due to bacterial infection. In humans, procalcitonin concentration has also been evaluated in milk in addition to plasma. The authors aimed to evaluate the possible application of a commercially available ELISA kit for bovine procalcitonin for the assessing of procalcitonin in bovine milk samples. Plasma and milk samples from cows with mastitis were collected to measure procalcitonin concentrations by using a bovine procalcitonin ELISA kit. Our results showed that the ELISA kit tested can be employed to assess bovine procalcitonin in plasma but not for analyzing milk samples.

Abstract

The aim was to evaluate the use of a bovine procalcitonin (PCT) ELISA kit (Cusabio, China) for assessing PCT in bovine milk samples. Validation was performed by using 10 plasma and corresponding milk samples from mastitic cows. The limit of detection (LOD) was calculated. The coefficient of variation (CV%) of the readings of five plasma samples measured five times in the same plate (intra-assay) and the CV% of the same five samples read five times in three separate plates was evaluated. Parallelism was determined by serial twofold dilutions of five plasma and corresponding milk samples. Milk samples were analyzed with and without centrifugation. Regarding plasma PCT, the method presented an inter- and intra-CV < 23.7% and parallelism had very good recovery values. The ELISA kit studied can measure bovine plasma PCT concentrations. The kit antibodies fail in binding PCT in milk samples because all centrifuged milk samples showed a lower LOD than blank samples. Only three uncentrifuged milk samples showed measurable PCT concentrations. Due to these results, the commercial ELISA kit investigated could not be employed for the detection of PCT in milk samples.

Age and Body Condition Influence the Post-Prandial Interleukin-1β Response to a High-Starch Meal in Horses

Older horses and those prone to obesity may be at a higher risk for inflammation than younger and leaner counterparts. Previous research indicated a postprandial elevation in plasma concentrations of interleukin-1β (IL-1β), a pro-inflammatory cytokine, after consuming 1.2 g of non-structural carbohydrates/kilogram of body weight. However, these studies utilized horses of mixed age and body condition. The current study evaluated post-prandial IL-1β concentrations in horses specifically comparing lean to over-conditioned and middle aged to older. Our results suggest that at least two weeks of daily consumption of a high non-structural carbohydrate diet is required to induce a post-prandial increase in IL-1β concentrations in younger and leaner horses. In opposition to this, older and over-conditioned horses experience plasma increased on the first day of feeding and thereafter. Feeding management practices of older and over-conditioned individuals should emphasize lower non-structural carbohydrate intakes and further research should elucidate mechanisms of IL-1β activation.

Evaluation of Plasmatic Procalcitonin in Healthy, and in Systemic Inflammatory Response Syndrome (SIRS) Negative or Positive Colic Horses

Simple Summary

Procalcitonin (PCT) increased in the case of systemic inflammatory response syndrome (SIRS), especially due to bacterial infection. The correlation between SIRS score and plasma PCT levels in horses have not been evaluated, and no studies investigated plasma PCT concentration over time. In the present study, PCT and SIRS score were evaluated in colic horses at admission to the hospital and at 24, 48, 72 and 96 h. Statistically differences were detected between healthy vs. all colic horses and between healthy vs. SIRS positive or SIRS negative horses. No correlation was observed between SIRS score and PCT. This suggests a role of plasmatic PCT as good biomarker for colic.

Abstract

Colic horses show systemic inflammatory response syndrome (SIRS) clinical signs. Procalcitonin (PCT) showed increased circulating levels in sick horses. This study compares plasma PCT concentrations in healthy vs. SIRS negative/positive colic horses over time, and evaluates PCT and SIRS score potential correlation, to verify the usefulness of PCT for the evaluation of SIRS severity. Ninety-one horses were included; 43/91 were healthy, on basis of physical examination, blood work and SIRS score (score = 0), while 48/91 were sick colic horses, classified as SIRS-negative (score < 2) and positive (score ≥ 2). Moreover, a 0–6 point-scale SIRS score was calculated (assessing mucous membrane color and blood lactate concentration). PCT was evaluated at admission, and at 24, 48, 72 and 96 h, using a commercial kit for equine species. We verified by the ANOVA test PCT differences between healthy vs. colic horses, healthy vs. SIRS-negative or SIRS-positive colic horses, at all sampling times, and the correlation between the SIRS score at admission with the SIRS score. Statistically significant differences were detected between healthy vs. all colic horses and between healthy vs. SIRS-positive or negative horses at all sampling times. No correlation was observed between the SIRS score at admission and PCT values. PCT was statistically higher in colic horses compared to the healthy ones, suggesting a role as a biomarker for colic.

Hemodynamic changes in cytokines, chemokines, acute phase proteins and prostaglandins in mares with subclinical endometritis

Apparently healthy mares with conception failure or embryonic loss may have subclinical endometritis (SE). Our objective was to document evidence of systemic immune responses against SE in mares. In apparently healthy (control) mares as well as those with chronic endometritis (ChE) or subacute suppurative endometritis (SSE), both considered classes of SE, serum concentrations of cytokines (IL-1β, IL-6, IL-10 and TNF_-α), chemokines (IL-8), acute phase protein (SAA), and plasma concentrations of prostaglandins (PGF_2α and PGE₂) were measured using validated enzyme linked immunoassays (EIA). Mixed-breed mares of known reproductive history, were used. Based on an endometrial cytological examination, mares were allocated into the following groups: healthy (control), ChE, and SSE (12, 26 and 11 mares, respectively). Serum concentrations of IL-6, IL-8 and IL-10 and plasma PGF_2α concentrations were increased (P < 0.01) in mares with SSE compared to healthy mares. Furthermore, serum concentrations of IL-6 (P < 0.05) and IL-10 (P < 0.05) were elevated in the ChE group compared to the healthy group whereas serum SAA (P < 0.01) and plasma PGE₂ (P < 0.05) were higher in healthy mares compared to ChE and SSE mares. However, serum concentrations of IL-1β and TNF_-α were not significantly different among groups. In conclusion, there were two novel findings: (1) development of serum testing for a set of biochemical markers has promise to explore the pathogenesis of inflammation in mares with SE; and (2) none of the individual biomarkers studied, excluding IL-8, was a significant predictor of SE. However, serum IL-6:IL-10 and IL-6:TNF_-α concentrations, as well as plasma PGE₂:PGF_2α ratios, may yield a novel diagnostic marker for chronic subclinical endometritis.

The Horse Gut Microbiome Responds in a Highly Individualized Manner to Forage Lignification

Although contributions of the equine gut microbiome to forage utilization are well recognized, the impact of alfalfa (Medicago sativa L.) lignification on the equine gut microbiome remains unknown; thus, we characterized microbial communities in the equine gut when feeding reduced lignin (RL) and conventional (CON) alfalfa hays to adult stock-type horses. Dietary treatments were fed to six horses in a crossover study. Experimental periods consisted of a 9-day dietary adaptation phase followed by a 5-day total fecal collection phase, during which horses were housed in individual box stalls and manure was removed on a continuous 24-hour basis. At 12-hour intervals, manure was mixed, frozen, and processed for V4, 16S rRNA amplicon MiSeq sequencing. Reduced lignin alfalfa did not shift microbiome composition equally across all horses; however, each subject's microbiome responded to hay lignin content in an individualized manner, mostly, in terms of beta diversity. Amplicon sequence variants affiliated to Akkermansia, Fibrobacter succinogenes, Treponema, and Paludibacter fluctuated significantly when RL alfalfa was fed, with abundance patterns unique to each horse. Horse-specific associations between individual gut microbiome traits and characteristics of the digested CON or RL alfalfa were also observed, mainly in regards to dry matter digestibility and mean fecal particle size. These results indicate that the horse gut microbiome responds in an individualized manner to changes in the amount of acid detergent lignin in alfalfa hay, potentially impacting several feed digestibility characteristics. The implications of these horse-specific responses to hay lignification, for metabolic health and performance, remain to be elucidated.

Effects of Advanced Age, Pituitary Pars Intermedia Dysfunction and Insulin Dysregulation on Serum Antioxidant Markers in Horses

The study aims to assess the impact of age, pituitary pars intermedia dysfunction (PPID) and insulin dysregulation (ID) in horses on selected oxidative stress markers. The study includes 32 horses, divided into three groups: “young” adult group (aged 8–16 years old) “geriatric” group (aged 18–24 years old) and the “PPID” group (aged 15–31 years old). The PPID group was further divided into two subgroups: PPID ID+ and PPID ID− based on presence or absence of ID. We measured serum antioxidant stress markers in all horses: total oxidant status (TOS), total antioxidant capacity (TAC), ceruloplasmin (CER), lipofuscin (LPS), malondialdehyde (MDA) and thiols concentrations (containing sulfhydryl group -SH) as well as enzymatic systems: total superoxide dismutase (SOD), cytoplasmic SOD (CuZnSOD), mitochondrial SOD activity (MnSOD). Total serum thiols were significantly lower in the geriatric group and in the PPID group compared to the young group. The MnSOD concentration was higher in the PPID ID+ group compared to the PPID ID−. LPS and MDA concentrations were lower in the PPID ID+ group compared to the PPID ID− group. In the selected study groups of horses, older age, the presence of PPID and ID in the case of PPID had no effect on the studied oxidative stress markers.