Molecular cloning and expression of equine calcitonin, calcitonin gene-related peptide-I, and calcitonin gene-related peptide-II

Case - Control study: Evaluation of plasma procalcitonin concentration as an indicator of inflammation in healthy and sick cows

This case - control study aims to evaluate Procalcitonin (PCT) plasma concentrations in healthy and hospitalized cows with a conclusive diagnosis of inflammation due to bacterial infection. Thirty-four healthy and 131 sick cows were included. Procalcitonin concentrations were assessed using an ELISA kit for cattle. Depending on whether sick cows received antimicrobial treatments prior to admission or not, they were divided in treated (TP) or not treated (NTP) subgroups. Mann-Whitney U tests were performed to determine differences between healthy vs sick cows, while Kruskal-Wallis with Dunn's multiple comparison test were applied for healthy vs sick subgroups. Receiver operating characteristic (ROC) analysis was performed to assess the optimal cut-off value. Kaplan-Meier survival curves were determined for cows belonging to the groups with PCT values below and above ROC cut-offs. Plasma PCT concentration was 200.1 (147.8-324.1) pg/mL and 361.6 (239.7-947.1) pg/mL in the healthy control and in the sick group, respectively (P < 0.001). The optimal cut-off value of plasma PCT concentration was 244.4 pg/mL (sensitivity 73.6%, specificity 60.0%). The plasma PCT concentration was 267.5 (210.3-771.2) pg/mL in the TP subgroup and 425.6 (253.1-1242) pg/mL in the NTP subgroup (P = 0.03). Cows with PCT above the ROC cut-off value had a reduced survival percentage and a higher mortality risk (P < 0.05). Procalcitonin showed the ability of differentiate healthy cows from hospitalized cows with a conclusive diagnosis of inflammation due to bacterial infection. Moreover, PCT was a good predictor of negative prognostic outcome.

Molecularly imprinted polymers as effective capturing receptors in a pseudo-ELISA immunoassay for procalcitonin detection in veterinary species

In this study, a new sandwich-type immunoenzymatic assay, based on a molecularly imprinted polymer (MIP) as an artificial antibody (pseudo-ELISA), was developed for the determination of procalcitonin (PCT) in veterinary species. The quantification of PCT in human medicine represents the state of the art for the diagnosis of sepsis; instead the clinical studies on the relevance of PCT as a sepsis predictor in veterinary patients are few, likely due to the total absence of validated assays. MIPs have been widely used as antibody mimics for important applications, and MIP-based sandwich assays have emerged as promising analytical tools for the detection of disease biomarkers. Herein, a polynorepinephrine (PNE)-based imprinted film was directly synthesized on the well surface of a 96-well plate. Subsequently, based on a commercial ELISA kit, the PCT quantification was accomplished via a colorimetric sandwich assay by replacing the capture antibody of the kit with the PNE-based MIP. This method was performed to detect canine and equine PCT in buffer and in plasma samples. Under optimal conditions, the results obtained in plasma samples showed a limit of detection (LOD) of 5.87 ng mL^-1 and a reproducibility (CV_av%) of 10.0% for canine samples, while a LOD = 4.46 ng mL^-1 and CV_av% = 7.61% were obtained for equine samples.

Measurement of procalcitonin in saliva of pigs: a pilot study

Background

Procalcitonin (PCT) is a widely used biomarker of sepsis in human medicine and can have potential applications in the veterinary field. This study aimed to explore whether PCT could be measured in the saliva of pigs and whether its concentration changes in sepsis. Therefore, a specific assay was developed and analytically validated, and changes in PCT concentration were evaluated in two conditions: a) in an experimental model of sepsis produced by the administration of lipopolysaccharide (LPS) to pigs (n = 5), that was compared with a model of non-septic inflammation induced by turpentine oil (n = 4), and b) in healthy piglets (n = 11) compared to piglets with meningitis (n = 20), a disease that usually involves sepsis and whose treatment often requires large amounts of antibiotics in farms.

Results

The assay showed coefficients of variation within the recommended limits and adequate linearity after serial sample dilutions. The method's detection limit was set at 68 μg/L, and the lower limit of quantification was 414 μg/L. In the LPS experiment, higher concentrations of PCT were found after 24 h in the animals injected with LPS (mean = 5790 μg/L) compared to those treated with turpentine oil (mean = 2127 μg/L, P = 0.045). Also, animals with meningitis had higher concentrations of PCT (mean = 21515 μg/L) than healthy pigs (mean = 6096 μg/L, P value < 0.0001).

Conclusions

According to these results, this assay could be potentially used as a tool for the non-invasive detection of sepsis in pigs, which is currently a topic of high importance due to antibiotic use restriction.

Beyond CGRP: The calcitonin peptide family as targets for migraine and pain

The CGRP system has emerged as a key pharmacological target for the treatment of migraine. However, some individuals who suffer from migraine have low or no response to anti-CGRP or other treatments, suggesting the need for additional clinical targets. CGRP belongs to the calcitonin family of peptides, which includes calcitonin, amylin, adrenomedullin and adrenomedullin 2. These peptides display a range of pro-nociceptive and anti-nociceptive actions, in primary headache conditions such as migraine. Calcitonin family peptides also show expression at sites relevant to migraine and pain. This suggests that calcitonin family peptides and their receptors, beyond CGRP, may be therapeutically useful in the treatment of migraine and other pain disorders. This review considers the localisation of the calcitonin family in peripheral pain pathways and discusses how they may contribute to migraine and pain. LINKED ARTICLES: This article is part of a themed issue on Advances in Migraine and Headache Therapy (BJP 75th Anniversary). To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.3/issuetoc.

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.

Detection of canine and equine procalcitonin for sepsis diagnosis in veterinary clinic by the development of novel MIP-based SPR biosensors

Procalcitonin (PCT) has emerged as a promising biomarker for the rapid identification of sepsis both in human and veterinary medicine. Nevertheless, the only analytical method currently available for the detection of PCT in veterinary species, is represented by immunoassays, useful only for research purposes. In this work, we report the development of two biosensors which utilize molecularly imprinted polymers (MIPs) for the detection of canine and equine PCT. Dopamine (DA) and norepinephrine (NE) were used as monomers for the synthesis of the MIP films on surface plasmon resonance (SPR) gold chips and the imprinting efficiency of canine and equine PCT in terms of binding affinity toward the analyte, selectivity, and sensitivity were compared. After optimization in buffer conditions, PCTs calibration was successfully achieved also in animal plasma, with good specificity and reproducibility. More effective protein binding and imprinting was obtained with polynorepinephrine (PNE) for both PCTs, and the SPR biosensors were able to detect the biomarkers in plasma with a LOD of 15 ng mL^-1 and 30 ng mL^-1 respectively for equine and canine PCT.

Procalcitonin Detection in Veterinary Species: Investigation of Commercial ELISA Kits

Simple Summary

Among sepsis biomarkers, procalcitonin resulted to be a specific indicator of bacterial infection or severity of infection, and to be a good control of the success of a therapeutic procedure. The clinical studies on the relevance of procalcitonin as a sepsis predictor in veterinary patients are few, likely due to the total absence of validated assays. For this reason, this study aimed to investigate commercial ELISA kits for the detection of canine and equine procalcitonin. Validation was performed evaluating linearity, limits of detection (LOD), recovery, and intra-assay and inter-assay variability; furthermore, clinical samples were analyzed. The results of the present study demonstrate that the human PCT ELISA kit is suitable to detect equine procalcitonin with a LOD of 56 ng/mL, and the canine recombinant PCT ELISA kit can be used to measure canine procalcitonin in plasma samples, showing an intra-assay and inter-assay coefficient of variation less than 20% and a LOD of 11 pg/mL.

Abstract

In human medicine, procalcitonin (PCT), the precursor of calcitonin, is used for the rapid identification of the origin and severity of sepsis. In veterinary medicine, PCT has been studied in horses, cattle, and dogs, but the use of PCT in diagnostic and/or prognostic settings is not possible because of the lack of validated assays to obtain reference ranges. The aim of the present study was the investigation of commercially available ELISA kits for the detection of canine and equine PCT in plasma samples. Validation of the ELISA kits was performed by using species-specific recombinant proteins spiked both in plasma and buffer samples; linearity, limit of detection (LOD), recovery, and intra-assay and inter-assay variability were calculated. Moreover, clinical samples obtained from sick and healthy animals were also analyzed with the tested kits. Canine PCT was measured with a recombinant canine and a canine PCT ELISA kit. Equine PCT was measured with an equine and a human ELISA PCT kit. Our data demonstrate that the canine recombinant PCT ELISA kit can be used to measure canine PCT in plasma samples, showing an intra-assay and inter-assay coefficient of variation less than 20% and a LOD of 11 pg/mL, whereas the present results do not support the use of the canine PCT ELISA kit. The human PCT ELISA kit is suitable to detect equine PCT with a LOD of 56 ng/mL, whereas the equine PCT ELISA kit did not detect recombinant equine PCT.

Plasma procalcitonin concentration in healthy calves and those with septic systemic inflammatory response syndrome

The diagnosis of sepsis in calves is challenging. Blood culture and clinical signs combined with a complete blood count have been used for the diagnosis of sepsis. Recent literature in humans and animal species has been focused on sepsis-specific biomarkers, such as procalcitonin (PCT), that may more accurately and efficiently diagnose sepsis. The aim of this study was to evaluate plasma PCT concentrations in healthy and septic calves. Twenty healthy control calves and 58 sick calves with septic systemic inflammatory response syndrome (SIRS) based on SIRS score and clinical findings were included. Calves with septic SIRS were further divided in septic SIRS survivors (SSS) and non-survivors (SSNS). Plasma PCT concentrations were measured with a commercial ELISA assay for cattle. A receiver operating characteristic curve was used to determine cut-off values and corresponding sensitivity and specificity for the diagnosis of sepsis. Differences in plasma PCT concentration between groups (control vs. SSS vs. SSNS) were evaluated. Plasma PCT concentrations in healthy calves and those with septic SIRS were 33.3pg/mL (0-44.3pg/mL) and 166.5pg/mL (85.9-233.0pg/mL), respectively (P<0.001). The optimal cut-off value to predict septic SIRS was 67.39pg/mL (81.0% sensitivity, 95.0% specificity). Plasma PCT concentrations were 127.4pg/mL (72.2-216.0pg/mL) and 234.3pg/mL (204.5-309.4pg/mL) in the SSS and SSNS subgroups, respectively. Statistically significant differences were found among groups (control vs. SSS and SSNS, P<0.0001; SSS vs. SSNS, P>0.05). These results confirmed an increase in plasma PCT concentrations in calves with septic SIRS, as previously reported in humans and other species.

Kinetics of plasma procalcitonin, soluble CD14, CCL2 and IL-10 after a sublethal infusion of lipopolysaccharide in horses

Endotoxemia represents a significant clinical and economic problem for the equine industry. This study assesses the kinetics of soluble CD14 (sCD14), chemokine (CC motif) ligand 2 (CCL2), interleukin 10 (IL-10) and plasma procalcitonin (PCT) in healthy horses after the intravenous infusion of lipopolysaccharide (LPS). The aim was to contribute to the basic understanding of the equine species-specific kinetics of these molecules in response to LPS exposure, which could support further findings in clinical studies and identify valuable inflammatory biomarkers for equine practice. Eleven healthy horses were involved in this experimental in vivo study. Horses were classified as healthy before the LPS infusion. After the pre-infusion blood collection (T0), all horses received an infusion of E. coli endotoxin (30ng/kg over 30min). Data and samples were collected 1h (T1), 2 (T2), 3 (T3) and 24h (T24) after infusion. Plasma sCD14, CCL2 and IL-10 were evaluated with a fluorescent bead-based assay, while PCT was evaluated with an equine PCT ELISA assay. A one-way ANOVA test was performed between each blood-sampling time for PCT, sCD14 and IL-10, and a Friedman test was performed for CCL2. Plasma PCT, IL-10 and CCL2 concentrations increased statistically significantly at T1, T2 and T3 compared to T0. No statistically significant differences were found between plasma IL-10 and CCL2 concentrations between T0 vs T24, although plasma PCT values remained high 24h after LPS infusion. Plasma sCD14 concentration showed no statistically significant differences for any of sampling times. Our results demonstrate that LPS injection into healthy horses results in PCT, CCL2 and IL-10 increases in plasma without an increase in sCD14. The increases in PCT, CCL2 and IL-10 are related to the inflammatory response induced by circulating lipopolysaccharide.

Procalcitonin as a biomarker in equine chronic pneumopathies

BACKGROUND

Procalcitonin (PCT), a precursor protein of the hormone calcitonin, is a sensitive inflammatory marker in human medicine, which is primarily used for diagnosis of bacterial sepsis, but is also useful in diagnosis of exacerbation of asthma and COPD. In this study, PCT was evaluated as a potential biomarker for different chronic pneumopathies in the horse using an equine specific ELISA in comparison to established clinical markers and different interleukins. Sixty-four horses were classified as free of respiratory disease, recurrent airway obstruction (RAO), inflammatory airway disease (IAD) or chronic interstitial pneumopathy (CIP) using a scoring system. PCT concentrations were measured in plasma (n = 17) and in the cell-free supernatant of bronchoalveolar lavage (n = 64). PCT concentrations were correlated to interleukins IL-1ß and IL-6 in BALF, clinical findings and BALF cytology.

RESULTS

The median PCT concentrations in plasma were increased in respiratory disease (174.46 ng/ml, n = 7) compared to controls (13.94 ng/ml, n = 10, P = 0.05) and correlated to PCT in BALF supernatant (rs = 0.48). Compared to controls (5.49 ng/ml, n = 15), median PCT concentrations in BALF supernatant correlated to the overall clinical score (rs = 0.32, P = 0.007) and were significantly increased in RAO (13.40 ng/ml, n = 21) and IAD (16.89 ng/ml, n = 16), while no differences were found for CIP (12.02 ng/ml, n = 12). No significant increases were found for IL-1 and IL-6 between controls and respiratory disease in general as well as different disease groups.

CONCLUSIONS

Although some correlations were found between PCT in plasma, BALF supernatant and clinical scores, PCT in BALF does not seem to be a superior marker compared to established clinical markers. PCT in plasma seems to be more promising and a greater number of samples should be evaluated in further studies.

Calcium-sensing receptor, proinflammatory cytokines and calcium homeostasis

The calcium-sensing receptor (CaSR) expressed in the parathyroid gland and the kidney tubule acts as the calciostat and orchestrates blood calcium homeostasis by modulating production and release of parathyroid hormone (PTH) and active vitamin D that influence Ca(2+) fluxes across the bone, kidney and intestine. Here we consider the role of the CaSR as a responder to proinflammatory cytokines released as part of the innate immune response to tissue injury and inflammation with resetting of the calciostat on the one hand and as a promoter and mediator of the initial inflammatory response on the other. The importance of the CaSR in systemic calcium homeostasis is exemplified by the fact that inactivating and activating mutations in the gene result in hypercalcemia and hypocalcemia, respectively. Proinflammatory cytokines interleukin-1β and interleukin-6 upregulate CaSR expression in parathyroid and kidney and do this through defined response elements in the CASR gene promoters. This results in decreased serum PTH and 1,25-dihydroxyvitamin D and calcium levels. This is likely to underlie the hypocalcemia that commonly occurs in critically ill patients, those with burn injury and sepsis, for example. The level of calcium in extracellular fluid bathing necrotic cells is often elevated and acts as a chemokine to attract monocytes/macrophages that express the CaSR to sites of tissue injury. Elevated levels of calcium acting via the CaSR can function as a danger signal that stimulates assembly of myeloid cell cytosolic multiprotein inflammasomes resulting in maturation of the proinflammatory cytokine IL-1β by caspase-1. Thus the CaSR is both promoter of and responder to the inflammation.

Plasma Procalcitonin Concentration in Healthy Horses and Horses Affected by Systemic Inflammatory Response Syndrome

BACKGROUND

The diseases most frequent associated with SIRS in adult horses are those involving the gastrointestinal tract. An early diagnosis should be the goal in the management of horses with SIRS.

OBJECTIVE

The objective of this study was to evaluate the plasma procalcitonin (PCT) concentration in healthy and SIRS horses to assess differences between the two groups.

ANIMALS

Seventy-eight horses (30 healthy and 48 SIRS).

METHODS

Prospective in vivo multicentric study. Horses were classified as SIRS if at least 2 of the following criteria were met: abnormal leukocyte count or distribution, hyperthermia or hypothermia, tachycardia, tachypnea. Healthy horses showed no clinical or laboratory signs of SIRS. Plasma PCT concentrations were measured with a commercial ELISA assay for equine species. Results were expressed as mean±standard deviation. T-test for unpaired data was performed between healthy and SIRS group. SIRS group was divided in 4 subgroups and t-test was performed between healthy versus each subgroup.

RESULTS

PCT concentrations in healthy and SIRS horses were 18.28 ± 20.32 and 197.0 ± 117.0 pg/mL, respectively. T-test showed statistical differences between healthy versus SIRS group and between healthy versus all subgroups.

CONCLUSIONS AND CLINICAL IMPORTANCE

Results showed an increase in PCT concentration in SIRS horses as previously reported in humans and dogs. PCT could be used as a single assay in equine practice for detection of SIRS.

The calcium-sensing receptor as a mediator of inflammation

The teleologic link between increased production of pro-inflammatory cytokines resulting from a systemic inflammatory response to a burn injury and consequent stimulation of bone resorption is unclear. While it is known that cytokines can stimulate osteocytic and osteoblastic production of the ligand of the receptor activator of NFκB, or RANKL, it is not certain why this occurs. It was therefore hypothesized that the subsequent osteoclastic bone resorption liberates calcium from the bone matrix and somehow affects the inflammatory response. In this paper we show how the cytokine-mediated inflammatory response following severe burn injury in children results in simultaneous increase in bone resorption and up-regulation of the parathyroid calcium-sensing receptor. The acute bone resorption leads to release of calcium from the bone matrix with consequent calcium accumulation in the circulation. The up-regulation of the parathyroid calcium-sensing receptor suppresses the release of parathyroid hormone resulting in a lowering of blood calcium concentration. The simultaneous occurrences of these processes could regulate blood calcium concentration and if calcium concentration affects the inflammatory response, then the calcium-sensing receptor could, at the very least, modulate the inflammatory response by adjusting the blood calcium concentration. We describe in vitro studies in which we demonstrated that peripheral blood mononuclear cells in culture produce the chemokines MIP-1α and RANTES in proportion to the medium calcium concentration and they produce the chemokine MCP-1 in quantities inversely related to medium calcium concentration. CD14+monocytes in culture will also produce MIP-1α in direct relationship to medium calcium concentration but the correlation coefficient is markedly reduced compared to that with peripheral blood mononuclear cells. These monocytes, which possess the calcium-sensing receptor, do not produce MCP-1 in either direct or inverse relationship to medium calcium concentration. Therefore, it is possible that other peripheral blood mononuclear cells are primarily responsible for the production of chemokines in relation to calcium concentration but these cells have not yet been defined.

A new ELISA for the quantification of equine procalcitonin in plasma as potential inflammation biomarker in horses

In human medicine, procalcitonin (PCT) is a very common and well-established biomarker for sepsis. Even though sepsis is also a leading cause of death in foals and adult horses, up to now, no data about the role of equine PCT in septic horses has been available. Based on monoclonal antibodies targeted against human PCT, we report here the development of a sandwich ELISA for the quantification of equine PCT in equine plasma samples. The ELISA was characterized for intra- and interassay variance and a working range from 25 to 1,000 ng mL(-1) was defined as within this range; both intra- and interassay variances were below 15 %. The target recovery ranged between 73 and 106 %. The ELISA was used to determine the equine PCT concentration in 24 healthy and 5 septic horses to show the potential for clinical evaluation of equine PCT. Significantly different (P = 0.0006) mean equine PCT concentrations were found for the healthy control group and the sepsis group (47 and 8,450 ng mL(-1)).

Endocrine dysregulation in critically ill foals and horses

Critical illness challenges many endocrine homeostatic systems to overcome diseases, stress, and hostile conditions that threaten survival. Coordinated and consecutive responses by the autonomic nervous system, endocrine metabolic adaptations to mobilize and conserve energy and electrolytes, cardiovascular adjustments to maintain organ perfusion, and immunomodulation to overcome infections and inflammation are required. Because most admissions to equine intensive care units are related to horses with gastrointestinal disease and septic foals, most endocrine information during critical disease are generated from these populations. This article presents an overview on endocrine responses to critical illness in horses and foals and also some comparative information.

Procalcitonin in sepsis and systemic inflammation: a harmful biomarker and a therapeutic target

The worldwide yearly mortality from sepsis is substantial, greater than that of cancer of the lung and breast combined. Moreover, its incidence is increasing, and its response to therapy has not appreciably improved. In this condition, the secretion of procalcitonin (ProCT), the prohormone of calcitonin, is augmented greatly, attaining levels up to thousands of fold of normal. This hypersecretion emanates from multiple tissues throughout the body that are not traditionally viewed as being endocrine. The serum values of ProCT correlate with the severity of sepsis; they recede with its improvement and worsen with exacerbation. Accordingly, as highlighted in this review, serum ProCT has become useful as a biomarker to assist in the diagnosis of sepsis, as well as related infectious or inflammatory conditions. It is also a useful monitor of the clinical course and prognosis, and sensitive and specific assays have been developed for its measurement. Moreover, it has been demonstrated that the administration of ProCT to septic animals greatly increases mortality, and several toxic effects of ProCT have been elucidated by in vitro experimental studies. Antibodies have been developed that neutralize the harmful effects of ProCT, and their use markedly decreases the symptomatology and mortality of animals that harbour a highly virulent sepsis analogous to that occurring in humans. This therapy is facilitated by the long duration of serum ProCT elevation, which allows for a broad window of therapeutic opportunity. An experimental groundwork has been established that suggests a potential applicability of such therapy in septic humans.

Calcitonin receptor-stimulating peptide: Its evolutionary and functional relationship with calcitonin/calcitonin gene-related peptide based on gene structure

This review focuses on the evolutionary and functional relationship of calcitonin receptor-stimulating peptide (CRSP) with calcitonin (CT)/calcitonin gene-related peptide (CGRP) in mammals. CRSP shows high sequence identity with CGRP, but distinct biological properties. CRSP genes (CRSPs) have been identified in mammals such as pigs and dogs of the Laurasiatheria, but not in primates and rodents of the Euarchontoglires or in non-placental mammals. CRSPs have genomic organizations highly similar to those of CT/CGRP genes (CT/CGRPs), which are located along with CGRPs in a locus between CYP2R1 and INSC, while the other members of the CGRP superfamily, adrenomedullin and amylin, show genomic organizations and locations distinct from CT, CGRP, and CRSP. Thus, we categorized these three peptides into the CT/CGRP/CRSP family. Non-placental mammals having one and placental mammals having multiple CT/CGRP/CRSP family genes suggests that multiplicity of CT/CGRP started at an early stage of mammalian evolution. In the placental mammals, Laurasiatheria generally possesses multiple CRSPs and only one CT/CGRP, while Euarchontoglires possesses CT/CGRP and CGRPbeta but no CRSP, indicating an increase in the diversity and multiplicity of this family of genes in mammalian evolution. Phylogenetic analysis suggests that some CRSPs have been generated very recently in mammalian evolution. Taken together, the increase in the number and complexity of the CT/CGRP/CRSP family genes may have due to evolutionary pressure to facilitate adaptation during mammalian evolution. In this regard, it is important to elucidate the physiological roles of CT, CGRP and CRSP from the viewpoint of the CT/CGRP/CRSP family even in Euarchontoglires.

Rapid calcitonin response to experimental hypercalcemia in healthy horses

Calcium has important physiological functions, and disorders of calcium homeostasis are frequent in horses. We have made important progress understanding equine calcium homeostasis; however, limited information on equine calcitonin (CT) is available, in part because of the lack of validated CT assays. To determine the CT response to high ionized calcium (Ca(2+)) concentrations in healthy horses, we induced hypercalcemia in 10 healthy horses using a calcium gluconate 23% solution (5mg/kg; 120 mL/500 kg horse) infused over 4 min. Four horses were infused with 120 mL of 0.9% NaCl and used as controls. We validated a human-specific CT radioimmunoassay for use in horses. Serum Ca(2+) concentrations increased from 6.2+/-0.3mg/dL to 9.9+/-0.5mg/dL (4 min; P<0.01). Serum CT increased from 16.7+/-8.0 pg/mL to 87.1+/-55.8 pg/mL at 2 min, and 102.5+/-51.1 pg/mL at 4 min (P<0.01). Serum CT returned to baseline by 20 min, whereas serum Ca(2+) returned to baseline by 40 min. Of interest, CT concentrations returned to baseline despite hypercalcemia, suggesting thyroid gland C-cell CT depletion. Resting CT values higher than 40 pg/mL were considered abnormally elevated. No significant changes in serum Ca(2+) or CT concentrations were found in control horses. The coefficients of variation for the CT radioimmunoassay were lower than 11.9%. We conclude that the equine thyroid gland C-cell responds quickly to changes in extracellular Ca(2+) concentrations by secreting large quantities of CT into the systemic circulation, indicating that CT is important in equine calcium homeostasis. The human CT radioimmunoassay can be used to measure changes in equine CT.

Structure and biological properties of three calcitonin receptor-stimulating peptides, novel members of the calcitonin gene-related peptide family

In this review, we describe the structure and biological properties of calcitonin receptor-stimulating peptide-1 (CRSP-1), CRSP-2 and CRSP-3, the novel members of the CGRP family. CRSP-1, which has been identified in the pig, cow, dog, and horse, is a specific ligand for the calcitonin (CT) receptor, and porcine CRSP-1 elicits a 100-fold greater effect on a recombinant porcine CT receptor than porcine CT, although this peptide has high structural similarity with CGRP. CRSP-1 is expressed and synthesized mainly in the central nervous system (CNS), pituitary and thyroid gland. In an in vivo experiment, bolus administration of CRSP-1 into rats reduced the plasma calcium concentration, but did not alter blood pressure, indicating its action as a CT receptor agonist in the peripheral circulation. In the CNS, CRSP-1 is also deduced to be an endogenous agonist for the CT receptor. CRSP-2 has been identified in the pig and dog, and CRSP-3 has been identified only in the pig. They are expressed and synthesized mainly in the CNS and thyroid gland. However, their endogenous molecular forms, receptors, and biological activity remain unidentified.

Identification, structural determination, and biological activity of bovine and canine calcitonin receptor-stimulating peptides

We have recently identified in porcine brain a series of new peptides, designated calcitonin receptor-stimulating peptide-1 (CRSP-1), CRSP-2, and CRSP-3, but failed to find their counterparts in humans and rodents by either database searching or experimental cross-hybridization. In this study, we isolated cDNAs encoding precursors of bovine CRSP-1, canine CRSP-1, and canine CRSP-2 from their thyroid cDNA libraries. Although the deduced mature amino acid sequences of bovine and canine CRSP-1s and canine CRSP-2 showed identity with their respective porcine CRSP counterparts, none of them had a C-terminal amide structure. In LLC-PK(1) cells endogenously expressing the calcitonin (CT) receptor, bovine and canine CRSP-1s enhanced the cAMP production, while canine CRSP-2 did not stimulate it at all. Equine CGRP-I had a high identity in its amino acid sequence with porcine CRSP-1 and stimulated LLC-PK(1) cells at a potency comparable to that of porcine CT. None of these CRSPs or equine CGRP-I stimulated the CT-like receptor, even in the presence of receptor activity-modifying proteins. These results demonstrate that CRSP-1, a new class of biologically active peptide, is present in animals evolutionarily close to pigs and induces its activity through the calcitonin receptor, suggesting a wide existence and common properties of this peptide in mammals.

Characterisation and distribution of calcitonin gene-related peptide in a primitive teleost, the eel, Anguilla anguilla and comparison with calcitonin

Radioimmunoassay (RIA), radioreceptor assay and chromatography were used to study the occurrence of calcitonin gene-related peptide (CGRP) in a primitive teleost, the eel, Anguilla anguilla. Immunologically and biologically active CGRP-like molecules were found in brain, heart, kidney, liver, spleen and ultimobranchial body with the higher concentrations in brain, spleen and heart. Gel exclusion chromatography of heart and spleen extracts followed by SDS-PAGE showed that the eel CGRP-like molecules presented a molecular weight between 3.30 and 3.95 kDa similar to that of human CGRP. The wide distribution of CGRP reflects its multiple role as brain neuromediator and peripheral paracrine effector as described in mammals. In comparison, the distribution of calcitonin (CT) was much more restricted, immunologically and biologically active CT-like molecules being localised in the ultimobranchial bodies (UBB) that is the site of CT synthesis in non-mammalian vertebrates. In plasma, CGRP-like concentrations were 10 to 100 higher than those of CT. These high concentrations in a primitive teleost strengthen the possible endocrine role of CGRP in early vertebrates and emphasise the important role of this hormone in evolution.

Calcitonin gene-related peptide as inflammatory mediator

Sensory neuropeptides have been proposed to play a key role in the pathogenesis of a number of respiratory diseases such as asthma, chronic obstructive pulmonary disease or chronic cough. Next to prominent neuropeptides such as tachykinins or vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP) has long been suggested to participate in airway physiology and pathophysiology. CGRP is a 37 amino-acid peptide which is expressed by nerve fibers projecting to the airways and by pulmonary neuroendocrine cells. The most prominent effects of CGRP in the airways are vasodilatation and in a few instances bronchoconstriction. A further pulmonary effect of CGRP is the induction of eosinophil migration and the stimulation of beta-integrin-mediated T cell adhesion to fibronectin at the site of inflammation. By contrast, CGRP inhibits macrophage secretion and the capacity of macrophages to activate T-cells, indicating a potential anti-inflammatory effect. Due to the complex pulmonary effects of CGRP with bronchoconstriction and vasodilatation and diverse immunomodulatory actions, potential anti-asthma drugs based on this peptide have not been established so far. However, targeting the effects of CGRP may be of value for future strategies in nerve modulation.