Peptides 60 (2014) 18–22
Contents lists available at ScienceDirect
Peptides journal homepage: www.elsevier.com/locate/peptides
Changes of PACAP level in cerebrospinal fluid and plasma of patients with severe traumatic brain injury Peter Bukovics a,b,1 , Endre Czeiter b,c,d,e,∗,1 , Krisztina Amrein a , Noemi Kovacs a , Jozsef Pal a , Andrea Tamas d,e, Terez Bagoly f, Zsuzsanna Helyes c,f, Andras Buki a,b,c,1, Dora Reglodi d,e,1 a
Department of Neurosurgery, University of Pecs, Pecs, Hungary MTA-PTE Clinical Neuroscience MR Research Group, Pecs, Hungary c Janos Szentagothai Research Centre, University of Pecs, Pecs, Hungary d MTA-PTE Lendulet PACAP Research Group, Pecs, Hungary e Department of Anatomy, University of Pecs, Pecs, Hungary f Department of Pharmacology and Pharmacotherapy, University of Pecs, Pecs, Hungary b
a r t i c l e
i n f o
Article history: Received 22 April 2014 Received in revised form 1 July 2014 Accepted 1 July 2014 Available online 10 July 2014 Keywords: Endogenous PACAP Plasma Cerebrospinal fluid Traumatic brain injury Neuroprotective Blood–brain barrier
a b s t r a c t PACAP has well-known neuroprotective potential including traumatic brain injury (TBI). Its level is up-regulated following various insults of the CNS in animal models. A few studies have documented alterations of PACAP levels in human serum. The time course of post-ictal PACAP levels, for example, show correlation with migraine severity. Very little is known about the course of PACAP levels following CNS injury in humans and the presence of PACAP has not yet been detected in cerebrospinal fluid (CSF) of subjects with severe TBI (sTBI). The aim of the present study was to determine whether PACAP occurs in the CSF and plasma (Pl) of patients that suffered sTBI and to establish a time course of PACAP levels in the CSF and Pl. Thirty eight subjects with sTBI were enrolled with a Glasgow Coma Scale ≤8 on admission. Samples were taken daily, until the time of death or for maximum 10 days. Our results demonstrated that PACAP was detectable in the CSF, with higher concentrations in patients with TBI. PACAP concentrations markedly increased in both Pl and CSF in the majority of patients 24–48 h after the injury stayed high thereafter. In cases of surviving patients, Pl and CSF levels displayed parallel patterns, which may imply the damage of the blood–brain barrier. However, in patients, who died within the first week, Pl levels were markedly higher than CSF levels, possibly indicating the prognostic value of high Pl PACAP levels. © 2014 Elsevier Inc. All rights reserved.
Introduction Severe traumatic brain injury (sTBI) is one of the major causes of death among young individuals in high income countries [23]. According to the WHO’s estimation, traumatic brain injury will be the third most frequent cause of death until 2020 all over the world [28]. Neurotrophic factors are important endogenous neuroprotectants that play a role in spontaneous recovery following different types of neuronal injuries and are promising therapeutic tools [5,17–19,37]. Multiple lines of recently collected evidences point to the neuroprotective effects of pituitary adenylate cyclase activating polypeptide (PACAP). This member of the vasoactive intestinal peptide (VIP)/secretin/glucagon peptide family was
∗ Corresponding author. Tel.: +36 20 557 6026. E-mail address: [email protected] (E. Czeiter). 1 P. Bukovics and E. Czeiter as well as A. Buki and D. Reglodi contributed equally to the present work. http://dx.doi.org/10.1016/j.peptides.2014.07.001 0196-9781/© 2014 Elsevier Inc. All rights reserved.
discovered as a hypothalamic peptide based on its potential to increase adenylate cyclase activity in the pituitary gland [27]. It is found in two forms, PACAP-27 and PACAP-38, with PACAP-38 being the major form [49]. PACAP is widely distributed in the nervous system and also in endocrine glands, cardiovascular, gastrointestinal and respiratory tracts. It is involved in the regulation of various physiological processes, such as feeding, reproduction, thermoregulation, catecholamine synthesis, motor activity, brain development and neuronal survival. PACAP has potent neurotrophic and neuroprotective actions in models of cerebral ischemia, Parkinson’s disease and retinal degeneration [2,3,5,30–35,38,39,42,45]. In spite of the similarities in the pathogenesis of ischemic and traumatic brain injuries [7], until the most recent years, only a few of studies have investigated the potential neuroprotective role of PACAP in traumatic brain or spinal cord injuries. In the extradural static weight compression model of spinal cord injury in rat, post-injury PACAP treatment significantly reduced the number of apoptotic cells in the injured spinal cord [8,21]. PACAP has also been shown to attenuate
P. Bukovics et al. / Peptides 60 (2014) 18–22
the increase of tumor necrosis factor after spinal cord transection [22]. In a focal traumatic brain injury (TBI) model, upregulation of PACAP mRNA was observed in parallel with decreased number of apoptotic cells [41]. Not only these studies primarily conducted in focal models of brain injury suggest that PACAP might be a promising tool to inhibit traumatic injuries of the central nervous system, but also our observations have demonstrated that PACAP successfully interfered with traumatically evoked diffuse axonal injury. In the last few years our laboratories extensively investigated the purported neuroprotective role of PACAP in a diffuse model of experimental TBI. First, we discovered that the administration paradigm proved successful in experimental stroke (125 g pre-injury, iv) did not exert beneficial effects in terms of inhibiting traumatically evoked axonal injury; however, intracerebroventricular (icv) injection of the same dose revealed significant axonoprotection [16,31]. We also established the dose-response curve for icv administration of PACAP, demonstrating that 100 g PACAP significantly reduced the density of damaged axons in the corticospinal tract. Further, our most recent observations indicate that a considerable therapeutic window exists for post-injury PACAP-treatment in diffuse experimental TBI, considering that significant axonoprotection could be observed when PACAP was administered 2 h post-injury [46]. On the basis of the above detailed observations PACAP is now considered as a potential candidate for clinical studies in TBI. In a PACAP-deficient mouse model of neuronal injury Armstrong and colleagues found that although motor neuron survival after axotomy was not significantly different in PACAP deficient vs. wild type mice, recovery of axon regeneration after crush injury was significantly delayed. This observation raises the novel hypothesis that endogenous PACAP is critically involved in a carefully controlled immune response that is necessary for proper nerve regeneration after injury [1]. Little is known about the functions of PACAP in humans. The presence of PACAP has been shown in rat and human blood. Radioimmunoassay (RIA) analysis of rat serum has revealed that PACAP-38 concentration is higher in the hypophyseal portal blood than in the peripheral circulation [15]. We have previously identified PACAP-38 in the rat plasma by mass spectrometry and provided evidence that PACAP is released from activated capsaicin-sensitive afferents into the circulation [20,29]. In light of the above the aims of our present study were (1) to determine the presence of PACAP in the cerebrospinal fluid (CSF) and the plasma of patients with severe TBI, (2) to compare PACAP levels in sTBI with controls and to gain an initial insight into the time course of PACAP levels after sTBI and (3) to implement pilot statistical analysis whether there is any significant correlation between the PACAP levels and the clinical outcome.
Patients and methods Study population characteristics Human blood and CSF samples were taken daily from 38 patients who suffered severe TBI and were admitted to Department of Neurosurgery, University of Pecs, Hungary. The main inclusion criterion was Glasgow Coma Scale (GCS) ≤8 on admission caused by sustained severe TBI less than 24 h before the enrollment. Exclusion criteria were age
Contents lists available at ScienceDirect
Peptides journal homepage: www.elsevier.com/locate/peptides
Changes of PACAP level in cerebrospinal fluid and plasma of patients with severe traumatic brain injury Peter Bukovics a,b,1 , Endre Czeiter b,c,d,e,∗,1 , Krisztina Amrein a , Noemi Kovacs a , Jozsef Pal a , Andrea Tamas d,e, Terez Bagoly f, Zsuzsanna Helyes c,f, Andras Buki a,b,c,1, Dora Reglodi d,e,1 a
Department of Neurosurgery, University of Pecs, Pecs, Hungary MTA-PTE Clinical Neuroscience MR Research Group, Pecs, Hungary c Janos Szentagothai Research Centre, University of Pecs, Pecs, Hungary d MTA-PTE Lendulet PACAP Research Group, Pecs, Hungary e Department of Anatomy, University of Pecs, Pecs, Hungary f Department of Pharmacology and Pharmacotherapy, University of Pecs, Pecs, Hungary b
a r t i c l e
i n f o
Article history: Received 22 April 2014 Received in revised form 1 July 2014 Accepted 1 July 2014 Available online 10 July 2014 Keywords: Endogenous PACAP Plasma Cerebrospinal fluid Traumatic brain injury Neuroprotective Blood–brain barrier
a b s t r a c t PACAP has well-known neuroprotective potential including traumatic brain injury (TBI). Its level is up-regulated following various insults of the CNS in animal models. A few studies have documented alterations of PACAP levels in human serum. The time course of post-ictal PACAP levels, for example, show correlation with migraine severity. Very little is known about the course of PACAP levels following CNS injury in humans and the presence of PACAP has not yet been detected in cerebrospinal fluid (CSF) of subjects with severe TBI (sTBI). The aim of the present study was to determine whether PACAP occurs in the CSF and plasma (Pl) of patients that suffered sTBI and to establish a time course of PACAP levels in the CSF and Pl. Thirty eight subjects with sTBI were enrolled with a Glasgow Coma Scale ≤8 on admission. Samples were taken daily, until the time of death or for maximum 10 days. Our results demonstrated that PACAP was detectable in the CSF, with higher concentrations in patients with TBI. PACAP concentrations markedly increased in both Pl and CSF in the majority of patients 24–48 h after the injury stayed high thereafter. In cases of surviving patients, Pl and CSF levels displayed parallel patterns, which may imply the damage of the blood–brain barrier. However, in patients, who died within the first week, Pl levels were markedly higher than CSF levels, possibly indicating the prognostic value of high Pl PACAP levels. © 2014 Elsevier Inc. All rights reserved.
Introduction Severe traumatic brain injury (sTBI) is one of the major causes of death among young individuals in high income countries [23]. According to the WHO’s estimation, traumatic brain injury will be the third most frequent cause of death until 2020 all over the world [28]. Neurotrophic factors are important endogenous neuroprotectants that play a role in spontaneous recovery following different types of neuronal injuries and are promising therapeutic tools [5,17–19,37]. Multiple lines of recently collected evidences point to the neuroprotective effects of pituitary adenylate cyclase activating polypeptide (PACAP). This member of the vasoactive intestinal peptide (VIP)/secretin/glucagon peptide family was
∗ Corresponding author. Tel.: +36 20 557 6026. E-mail address: [email protected] (E. Czeiter). 1 P. Bukovics and E. Czeiter as well as A. Buki and D. Reglodi contributed equally to the present work. http://dx.doi.org/10.1016/j.peptides.2014.07.001 0196-9781/© 2014 Elsevier Inc. All rights reserved.
discovered as a hypothalamic peptide based on its potential to increase adenylate cyclase activity in the pituitary gland [27]. It is found in two forms, PACAP-27 and PACAP-38, with PACAP-38 being the major form [49]. PACAP is widely distributed in the nervous system and also in endocrine glands, cardiovascular, gastrointestinal and respiratory tracts. It is involved in the regulation of various physiological processes, such as feeding, reproduction, thermoregulation, catecholamine synthesis, motor activity, brain development and neuronal survival. PACAP has potent neurotrophic and neuroprotective actions in models of cerebral ischemia, Parkinson’s disease and retinal degeneration [2,3,5,30–35,38,39,42,45]. In spite of the similarities in the pathogenesis of ischemic and traumatic brain injuries [7], until the most recent years, only a few of studies have investigated the potential neuroprotective role of PACAP in traumatic brain or spinal cord injuries. In the extradural static weight compression model of spinal cord injury in rat, post-injury PACAP treatment significantly reduced the number of apoptotic cells in the injured spinal cord [8,21]. PACAP has also been shown to attenuate
P. Bukovics et al. / Peptides 60 (2014) 18–22
the increase of tumor necrosis factor after spinal cord transection [22]. In a focal traumatic brain injury (TBI) model, upregulation of PACAP mRNA was observed in parallel with decreased number of apoptotic cells [41]. Not only these studies primarily conducted in focal models of brain injury suggest that PACAP might be a promising tool to inhibit traumatic injuries of the central nervous system, but also our observations have demonstrated that PACAP successfully interfered with traumatically evoked diffuse axonal injury. In the last few years our laboratories extensively investigated the purported neuroprotective role of PACAP in a diffuse model of experimental TBI. First, we discovered that the administration paradigm proved successful in experimental stroke (125 g pre-injury, iv) did not exert beneficial effects in terms of inhibiting traumatically evoked axonal injury; however, intracerebroventricular (icv) injection of the same dose revealed significant axonoprotection [16,31]. We also established the dose-response curve for icv administration of PACAP, demonstrating that 100 g PACAP significantly reduced the density of damaged axons in the corticospinal tract. Further, our most recent observations indicate that a considerable therapeutic window exists for post-injury PACAP-treatment in diffuse experimental TBI, considering that significant axonoprotection could be observed when PACAP was administered 2 h post-injury [46]. On the basis of the above detailed observations PACAP is now considered as a potential candidate for clinical studies in TBI. In a PACAP-deficient mouse model of neuronal injury Armstrong and colleagues found that although motor neuron survival after axotomy was not significantly different in PACAP deficient vs. wild type mice, recovery of axon regeneration after crush injury was significantly delayed. This observation raises the novel hypothesis that endogenous PACAP is critically involved in a carefully controlled immune response that is necessary for proper nerve regeneration after injury [1]. Little is known about the functions of PACAP in humans. The presence of PACAP has been shown in rat and human blood. Radioimmunoassay (RIA) analysis of rat serum has revealed that PACAP-38 concentration is higher in the hypophyseal portal blood than in the peripheral circulation [15]. We have previously identified PACAP-38 in the rat plasma by mass spectrometry and provided evidence that PACAP is released from activated capsaicin-sensitive afferents into the circulation [20,29]. In light of the above the aims of our present study were (1) to determine the presence of PACAP in the cerebrospinal fluid (CSF) and the plasma of patients with severe TBI, (2) to compare PACAP levels in sTBI with controls and to gain an initial insight into the time course of PACAP levels after sTBI and (3) to implement pilot statistical analysis whether there is any significant correlation between the PACAP levels and the clinical outcome.
Patients and methods Study population characteristics Human blood and CSF samples were taken daily from 38 patients who suffered severe TBI and were admitted to Department of Neurosurgery, University of Pecs, Hungary. The main inclusion criterion was Glasgow Coma Scale (GCS) ≤8 on admission caused by sustained severe TBI less than 24 h before the enrollment. Exclusion criteria were age
