Plasma proteomics shows an elevation of the anti-inflammatory protein APOA-IV in chronic equine laminitis

A veterinary cerumenomic assay for bovine laminitis identification

Bovine laminitis disorder results in animal welfare and economic concerns in dairy and beef farms worldwide. However, the affected metabolic pathways, pathophysiologic characteristics, and inflammatory mechanisms remain unclear, hampering the development of new diagnostics. Using cerumen (earwax) as a source of volatile metabolites (cerumenomic) that carry valuable biological information has interesting implications for veterinary medicine. Nonetheless, up to now, no applications of veterinary cerumenomic assays have been made to identify bovine laminitis. This work aims to develop a veterinary cerumenomic assay for bovine laminitis identification that is non-invasive, robust, accurate, and sensitive to detecting the metabolic disturbances in bovine volatile metabolome. Twenty earwax samples (10 from healthy/control calves and 10 from laminitis calves) were collected from Nellore cattle, followed by Headspace/Gas Chromatography-Mass Spectrometry (HS/GC-MS) analysis and biomarker selection in two multivariate approaches: semiquantitative (intensity data) and semiqualitative (binary data). Following the analysis, cerumen volatile metabolites were indicated as candidate biomarkers for identifying bovine laminitis by monitoring their intensity or occurrence. In the semiquantitative strategy, the p-cresol presented the highest diagnostic figures of merit (area under the curve: 0.845, sensitivity: 0.700, and specificity: 0.900). Regarding the binary approach, a panel combining eight variables/volatiles, with formamide being the most prominent one, showed an area under the curve, sensitivity, and specificity of 0.97, 0.81, and 0.90, respectively. In summary, this work describes the first veterinary cerumenomic assay for bovine laminitis that indicates new metabolites altered during the inflammatory condition, paving the way for developing laminitis early diagnosis by monitoring the cerumen metabolites.

Characterizing the Serum Proteome of Donkeys (Equus asinus)

Serum and plasma are commonly used in clinical practice considering the widely accepted fact that the "normal" protein expression pattern of a healthy animal changes under disease conditions. We herein used a label-free mass spectrometry-based quantitative proteomics approach to characterize the serum proteome of donkeys. A total of 277 unique proteins were identified from 2,388 unique peptides. Gene ontology analyses showed that the most frequent processes were related to metabolic activities and biological regulation, response to stimulus, and immune system processes. The main annotated areas of origin were the extracellular region, extracellular region part, and organelle, and their molecular functions included binding, catalytic activity, and molecular function regulator. Analyses using the Clusters of Orthologous Groups for Eukaryotic Complete Genomes database indicated that the identified proteins could be categorized into three main groups: signal transduction mechanisms, amino acid transport and metabolism, and defense mechanisms. Most of the unique proteins were associated with the complement and coagulation cascades, and they participated in several disease-related metabolic pathways. Our results should be crucial for further analyses of changes in different physiological and pathophysiological conditions in donkeys.

In slow pace towards the proteome of equine body fluids

Equine medicine represents a relevant field of veterinary science and the horse industry generates a significant economic impact. Horses can be involved in different sport disciplines, meat production, work and recreational purposes. Horses are also important for human health as they can be used as animal models for studying human diseases and in equine-assisted therapy. This review summarizes the data related to body fluids such as plasma/serum, urine, cerebrospinal fluid, synovial fluid, saliva, bronchoalveolar lavage fluid and peritoneal fluid obtained using proteomic analysis. Horse body fluid proteome analysis under various physiological and pathological conditions is a useful method for identifying new biomarkers for horse diseases which are still difficult to diagnose, but with serious consequences on equine health and welfare. The findings reported here reveal that further proteomic studies on equine body fluids collected from diseased animals are required. SIGNIFICANCE: Body fluids are sources of potential protein biomarkers for diagnosis and therapeutic target identification. Indeed, they contain proteins that play a crucial role in cell functions and whose presence or relative abundance are indicative of the health status of tissues/organs. The review reports the data on the equine body fluids obtained using proteomic analysis, including those which are commonly used to obtain a correct diagnosis and prognosis of horse diseases which still pose a significant challenge. For equine medicine, new biomarkers are needed to formulate early diagnosis and to distinguish among diseases with similar clinical signs.

Differential Proteomic Expression of Equine Cardiac and Lamellar Tissue During Insulin-Induced Laminitis

Endocrinopathic laminitis is pathologically similar to the multi-organ dysfunction and peripheral neuropathy found in human patients with metabolic syndrome. Similarly, endocrinopathic laminitis has been shown to partially result from vascular dysfunction. However, despite extensive research, the pathogenesis of this disease is not well elucidated and laminitis remains without an effective treatment. Here, we sought to identify novel proteins and pathways underlying the development of equine endocrinopathic laminitis. Healthy Standardbred horses (n = 4/group) were either given an electrolyte infusion, or a 48-h euglycemic-hyperinsulinemic clamp. Cardiac and lamellar tissues were analyzed by mass spectrometry (FDR = 0.05). All hyperinsulinemic horses developed laminitis despite being previously healthy. We identified 514 and 709 unique proteins in the cardiac and lamellar proteomes, respectively. In the lamellar tissue, we identified 14 proteins for which their abundance was significantly increased and 13 proteins which were significantly decreased in the hyperinsulinemic group as compared to controls. These results were confirmed via real-time reverse-transcriptase PCR. A STRING analysis of protein-protein interactions revealed that these increased proteins were primarily involved in coagulation and complement cascades, platelet activity, and ribosomal function, while decreased proteins were involved in focal adhesions, spliceosomes, and cell-cell matrices. Novel significant differentially expressed proteins associated with hyperinsulinemia-induced laminitis include talin−1, vinculin, cadherin-13, fibrinogen, alpha-2-macroglobulin, and heat shock protein 90. In contrast, no proteins were found to be significantly differentially expressed in the heart of hyperinsulinemic horses compared to controls. Together, these data indicate that while hyperinsulinemia induced, in part, microvascular damage, complement activation, and ribosomal dysfunction in the lamellae, a similar effect was not seen in the heart. In brief, this proteomic investigation of a unique equine model of hyperinsulinemia identified novel proteins and signaling pathways, which may lead to the discovery of molecular biomarkers and/or therapeutic targets for endocrinopathic laminitis.

The Equine Hoof: Laminitis, Progenitor (Stem) Cells, and Therapy Development

The equine hoof capsule, composed of modified epidermis and dermis, is vital for protecting the third phalanx from forces of locomotion. There are descriptions of laminitis, defined as inflammation of sensitive hoof tissues but recognized as pathologic changes with or without inflammatory mediators, in the earliest records of domesticated horses. Laminitis can range from mild to serious, and signs can be acute, chronic, or transition from acute, severe inflammation to permanently abnormal tissue. Damage within the intricate dermal and epidermal connections of the primary and secondary lamellae is often associated with lifelong changes in hoof growth, repair, and conformation. Decades of research contribute to contemporary standards of care that include systemic and local therapies as well as mechanical hoof support. Despite this, consistent mechanisms to restore healthy tissue formation following a laminitic insult are lacking. Endogenous and exogenous progenitor cell contributions to healthy tissue formation is established for most tissues. There is comparably little information about equine hoof progenitor cells. Equine hoof anatomy, laminitis, and progenitor cells are covered in this review. The potential of progenitor cells to advance in vitro equine hoof tissue models and translate to clinical therapies may significantly improve prevention and treatment of a devastating condition that has afflicted equine companions throughout history.

Optimisation of a serum albumin removal protocol for use in a proteomic study to identify the protein biomarkers for silent gastric ulceration in horses

Silent gastric ulceration occurs without evidence of clinical signs and is common in horses. There is currently no a simple and effective method to diagnose this disease. Proteomics can be used to identify serum biomarkers, but the most abundant serum protein, albumin, could conceal candidate biomarkers. Therefore, it is recommended to remove albumin before a proteomic study; however, there is no specific albumin depletion kit or standard protocol available for horse samples. The objectives of this study were to optimise a protocol to remove equine serum albumin and to use albumin-depleted serum to identify the protein biomarkers for silent gastric ulceration. Gastroscopy was used to identify gastric ulceration, and serum was obtained from horses with either a healthy gastric mucosa or gastric ulceration. Serum albumin was removed using the trichloroacetic acid (TCA) protein precipitation method, and this protocol was optimised by varying the concentration of TCA, type of organic solvents, ratio of serum to protein precipitation solution, and incubation times. Electrophoresis and image analysis were used to compare the amounts of albumin, immunoglobulins G (IgG), and protein degradation before and after TCA precipitation. The best protocol was chosen to remove albumin for a proteomic study (electrophoresis and mass spectrometry). The results revealed that protocol 2 (ratio of serum to solution 1:5, 10% TCA in acetone, and 90 min incubation) was the most efficient protocol to remove albumin (98%) and IgG heavy (80%) and light (98%) chains without degrading other proteins. After electrophoresis and mass spectrometry analysis, KRT1, KRT6A and KRT18 were identified as potential markers for silent gastric ulceration.

Proteomics and metabolomics characterizing the pathophysiology of adaptive reactions to the metabolic challenges during the transition from late pregnancy to early lactation in dairy cows

The transition from late pregnancy to early lactation is a critical period in a dairy cow's life due to the rapidly increasing drain of nutrients from the maternal organism towards the foetus and into colostrum and milk. In order to cope with the challenges of parturition and lactation, comprehensive adaptive reactions comprising the endocrine and the immune system need to be accomplished. There is high variation in this coping ability and both metabolic and infectious diseases, summarized as "production diseases", such as hypocalcaemia (milk fever), fatty liver syndrome, laminitis and ketosis, may occur and impact welfare, productive lifespan and economic outcomes. Proteomics and metabolomics have emerged as valuable techniques to characterize proteins and metabolite assets from tissue and biological fluids, such as milk, blood and urine. In this review we provide an overview on metabolic status and physiological changes during the transition period and the related production diseases in dairy cows, and summarize the state of art on proteomics and metabolomics of biological fluids and tissues involved in metabolic stress during the peripartum period. We also provide a current and prospective view of the application of the recent achievements generated by omics for biomarker discovery and their potential in diagnosis.

BIOLOGICAL SIGNIFICANCE

For high-yielding dairy cows there are several "occupational diseases" that occur mainly during the metabolic challenges related to the transition from pregnancy to lactation. Such diseases and their sequelae form a major concern for dairy production, and often lead to early culling of animals. Beside the economical perspective, metabolic stress may severely influence animal welfare. There is a multitude of studies about the metabolic backgrounds of such so called production diseases like ketosis, fatty liver, or hypocalcaemia, although the investigations aiming to assess the complexity of the pathophysiological reactions are largely focused on gene expression, i.e. transcriptomics. For extending the knowledge towards the proteome and the metabolome, the respective technologies are of increasing importance and can provide an overall view of how dairy cows react to metabolic stress, which is needed for an in-depth understanding of the molecular mechanisms of the related diseases. We herein review the current findings from studies applying proteomics and metabolomics to transition-related diseases, including fatty liver, ketosis, endometritis, hypocalcaemia and laminitis. For each disease, a brief overview of the up to date knowledge about its pathogenesis is provided, followed by an insight into the most recent achievements on the proteome and metabolome of tissues and biological fluids, such as blood serum and urine, highlighting potential biomarkers. We believe that this review would help readers to be become more familiar with the recent progresses of molecular background of transition-related diseases thus encouraging research in this field.

Comparative proteomics analysis provide novel insight into laminitis in Chinese Holstein cows

Background

Laminitis is considered as the most important cause of hoof lameness in dairy cows, which causes abundant economic losses in husbandry. Through intense efforts in past decades, the etiology of laminitis is preliminarily considered to be subacute ruminal acidosis; however, the pathogenesis of laminitis needs further research. The differentially expressed proteins (DEP) were detected in plasma of healthy cows and clinical laminitis cows by two-dimensional gel electrophoresis (2-DE) and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Results

Nineteen protein spots were differentially expressed, and 16 kinds of proteins were identified after peptide mass fingerprint search and bioinformatics analysis. Of these, 12 proteins were differentially up-regulated and 4 down-regulated. Overall, these differential proteins were involved in carbohydrate metabolism, lipids metabolism, molecular transport, immune regulation, inflammatory response, oxidative stress and so on.

Conclusions

The DEPs were closely related to the occurrence and development of laminitis and the lipid metabolic disturbance may be a new pathway to cause laminitis in dairy cows. The results provide the theory foundation for further revealing the mechanism of laminitis and screening the early diagnostic proteins and therapeutic target.

Serum metabolomics identifies citrulline as a predictor of adverse outcomes in an equine model of gut-derived sepsis

Acute laminitis is an inflammatory disease of the equine foot that often occurs secondarily to sepsis or systemic inflammation associated with gastrointestinal disease. It has been suggested that laminitis is similar to multiple organ dysfunction syndrome in humans, although in horses the weight-bearing laminar epithelium of the foot appears to be the tissue most sensitive to insult and the first "organ" to fail. Metabolomics performed on serum samples collected before (Con) and after (Lmn) experimental induction of gastrointestinal-associated sepsis in six horses detected 1,177 metabolites of both mammalian and bacterial origin in equine serum. Network and correlation analyses suggested a dysregulation of fatty acid metabolism in the Lmn group, as well as an accumulation of organic acids such as lactate. Furthermore, concentrations of the amino acid citrulline were decreased in Lmn samples from all study animals, suggesting that citrulline might be useful as a biomarker to identify critically ill animals that are at risk of developing laminitis. We therefore established normal ranges of plasma citrulline concentrations in a separate group of horses (n = 36) and tested the ability of citrulline to predict adverse outcomes (laminitis or death) in critically ill horses (n = 23). Plasma citrulline was significantly lower in critically ill horses that went on to experience adverse outcomes (n = 6). Further study is required to accurately determine a diagnostic cutoff, but the present data are suggestive of the predictive value of citrulline as a biomarker for laminar failure in equine sepsis.

Proteomics in Veterinary Medicine

Advancement in electrophoresis and mass spectrometry techniques along with the recent progresses in genomics, culminating in bovine and pig genome sequencing, widened the potential application of proteomics in the field of veterinary medicine. The aim of the present review is to provide an in-depth perspective about the application of proteomics to animal disease pathogenesis, as well as its utilization in veterinary diagnostics. After an overview on the various proteomic techniques that are currently applied to veterinary sciences, the article focuses on proteomic approaches to animal disease pathogenesis. Included as well are recent achievements in immunoproteomics (ie, the identifications through proteomic techniques of antigen involved in immune response) and histoproteomics (ie, the application of proteomics in tissue processed for immunohistochemistry). Finally, the article focuses on clinical proteomics (ie, the application of proteomics to the identification of new biomarkers of animal diseases).

Effects of histidine-rich glycoprotein on cerebral blood vessels

Delayed cerebral vasospasm is thought to be caused by factors released from a subarachnoid blood clot. Because vasospasm occurs several days after hemorrhage, we hypothesized that clotted blood releases vasoactive factors as it ages. Targeted proteomics identified histidine-rich glycoprotein (HRG) as a potentially vasoactive factor released within the first 72 hours of clot formation. In vitro studies revealed that HRG caused moderate (~30%) dilation of cannulated cerebral arterioles and proliferation of cerebrovascular endothelial cells. We conclude that HRG released from clotted blood, while unlikely to contribute to cerebral vasospasm, might provide important vasodilatory or angiogenic stimuli after hemorrhagic stroke.

Cellular and humoral immunity in chronic equine laminitis

Chronic equine laminitis causes persistent pain and lameness in affected animals and often necessitates euthanasia when pain management strategies become ineffective. Published studies as well as anecdotal reports suggest that this chronic inflammatory disease is associated with systemic alterations in immune responsiveness, perhaps involving an autoimmune component. We investigated this broad hypothesis by measuring a variety of immune indicators in healthy control horses (CON) and horses with chronic laminitis (LMN). We found that white blood cells from LMN horses produced more IFNγ than did cells from CON horses when stimulated in vitro with polyinosinic-polycytidylic acid [poly(I:C)], possibly due to an elevated number of circulating monocytes. No differences between groups were observed in plasma concentrations of IgG, IgA, IgM, IgE, or rheumatoid factor. Laminar tissue from LMN horses expressed elevated levels of keratinocyte damage-related genes as well as inflammatory cytokines and chemokines, which corresponded with a modest amount of neutrophil infiltration as shown by histological staining of fixed tissue and accumulation of neutrophil elastase protein. Taken together, our results do not support the hypothesis of an autoimmune component in chronic laminitis, although the strong induction of neutrophil chemokines and the presence of tissue neutrophils suggests that this cell type is likely involved in perpetuating the inflammation and tissue damage associated with this disease.