Plasma pituitary adenylate cyclase activating polypeptide (PACAP) levels in chronic hepatitis B patients under lamivudine treatment

Role of endocrine PACAP in age-related diseases

Pituitary adenylate cyclase activating polypeptide (PACAP) is a conserved neuropeptide, which confers diverse anti-aging endocrine and paracrine/autocrine effects, including anti-apoptotic, anti-inflammatory and antioxidant action. The results of the in vivo and in vitro experiments show that increasing emphasis is being placed on the diagnostic/prognostic biomarker potential of this neuropeptide in a wide array of age-related diseases. After the initial findings regarding the presence and alteration of PACAP in different body fluids in physiological processes, an increasing number of studies have focused on the changes of its levels in various pathological conditions associated with advanced aging. Until 2016 - when the results of previous human studies were reviewed - a vast majority of the studies had dealt with age-related neurological diseases, like cerebrovascular and neurodegenerative diseases, multiple sclerosis, as well as some other common diseases in elderly such as migraine, traumatic brain injury and post-traumatic stress disorder, chronic hepatitis and nephrotic syndrome. The aim of this review is to summarize the old and the new results and highlight those 'classical' and emerging clinical fields in which PACAP may become subject to further investigation as a diagnostic and/or prognostic biomarker in age-related diseases.

Changes of pituitary adenylate cyclase activating polypeptide (PACAP) level in polytrauma patients in the early post-traumatic period

In polytrauma patients who survive the primary insult, the imbalance between the pro- and anti-inflammatory processes seems to be responsible for life-threatening complications such as sepsis or multiple organ dysfunction syndrome. Measurement of C-reactive protein (CRP) and procalcitonin (PCT) is a standard way for differentiating between infectious (bacterial) and non-infectious inflammation. Monitoring of immune cell functions, like leukocyte anti-sedimentation rate (LAR) can also be useful to diagnose infectious complications. Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide with well-known immunomodulatory and anti-inflammatory effects. The aim of our study was to determine the changes of PACAP38 levels in polytrauma patients in the early post-traumatic period in intensive care unit and analyse possible correlation of its level with conventional (CRP, PCT) and unconventional (LAR) laboratory parameters. Twenty polytrauma patients were enrolled. Blood samples were taken daily for five days. We observed significant correlation between PACAP38 and CRP levels on day 4 and 5 as well as between PACAP38 and LAR levels all of the days. This could be due to the anti-inflammatory and cytoprotective functions of PACAP38 as part of an endogenous response to the trauma induced systemic inflammatory response syndrome. These significant correlations could have clinical importance in monitoring the dynamic balance of pro- and anti-inflammatory processes in case of polytraumatic patients.

Pituitary adenylate cyclase-activating peptide: Potential roles in the pathophysiology and complications of cirrhosis

Pituitary adenylate cyclase-activating peptide (PACAP) is a ubiquitous neuropeptide with diverse functions throughout the organism. Most abundantly investigated for its role in several neurological disorders as well as in circadian rhythms, other fields of medicine, including cardiology, have recently shown interest in the role of PACAP and its potential as a biomarker. Timely diagnosis and treatment of cirrhosis and its complications is a considerable challenge for health services world-wide and development of new areas of research is warranted. Direct and indirect evidence exists of PACAP involvement in the cascade of pathological events and processes ultimately leading to cirrhosis and its complications, but its exact role remains to be determined. Studies have documented PACAP involvement in immune function, metabolism, local vasoconstriction and dilatation and systemic vascular decompensation and there is ongoing research of a possible role in liver reperfusion injury. Considering these reports, PACAP could theoretically exude influence on the disease course of cirrhosis through the hypothalamus-pituitary-adrenal axis, chronic inflammation, fibrogenesis, vasodilation and reduced vascular resistance. The paucity of literature on the specific topic of PACAP and cirrhosis reflects complex mechanisms and difficulty in accurate measurements and sample taking. This does not detract from the need to further characterize and elucidate the role PACAP plays in the underdiagnosed and undertreated condition of cirrhosis.

Antimicrobial peptides: a promising strategy for lung cancer drug discovery?

INTRODUCTION

Antimicrobial peptides (AMPs), also called host defense peptides (HDPs), are identified in almost any form of life, which play an important role in innate immune systems. They have a broad spectrum of antifungal, antiviral, antibacterial, and anticancer activities. Lung cancer remains the leading cause of global cancer-related death. Unfortunately, lung cancer chemotherapy is accompanied by serious side effects, nonspecific toxicity, and multidrug resistance. Hence, to overcome these drawbacks, anticancer peptides (ACPs) derived from AMPs may represent a potential promising synergistic treatment strategy for lung cancer.

AREAS COVERED

In this review, the authors provide the recent advancements in the use of AMPs for the treatment of lung cancer. Furthermore, the anti-lung cancer modes of action of these peptides have been fully reviewed. Importantly, various strategies for increasing the efficiency and safety of AMPs have been discussed.

EXPERT OPINION

The combination of AMPs and other cancer treatment approaches such as chemotherapy, nanoparticle-based delivery systems, and photodynamic therapy can be used as a promising revolutionary strategy for the treatment of lung cancer. The most significant limitations of this strategy that need to be focused on are low efficiency and off-target events.

First in vivo evidence of pituitary adenylate cyclase-activating polypeptide antiviral activity in teleost

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a multifunctional neuropeptide belonging to the glucagon/secretin superfamily. In teleost fish, PACAP has been demonstrated to have an immunomodulatory role. Although previous studies have shown that viral/bacterial infections can influence the transcription of PACAP splicing variants and associated receptors in salmonids, the antiviral activity of PACAP has never been studied in teleost. Thus, in the present work, we investigated in vitro the influence of synthetic Clarias gariepinus PACAP-38 on the transcription of genes related to viral immunity using the rainbow trout monocyte/macrophage-like cell line RTS11 as a model. Positive transcriptional modulation of interferon gamma (IFNγ), interferon alpha (FNα1,2), interleukin 8 (IL-8), Mx and Toll-like receptor 3 (TLR3) genes was found in a dose and time dependent manner. We also explored how a pre-treatment with PACAP could enhance antiviral immune response using poly (I:C) as viral mimic. Interferons and IL-8 transcription levels were enhanced when PACAP was added 24 h previous to poly (I:C) exposure. With these evidences, we tested in vivo how PACAP administration by immersion bath affected the survival of rainbow trout fry to a challenge with viral hemorrhagic septicemia virus (VHSV). After challenge, PACAP-treated fish had increased survival compared to non-treated/challenge fish. Furthermore, PACAP was able to decrease the viral load in spleen/kidney and stimulate the transcription of IFNs and Mx when compared to untreated infected fish. Altogether, the results of this work provide valuable insights regarding the role of teleost PACAP in antiviral immunity and point to a potential application of this peptide to reduce the impact of viral infections in aquaculture.

Evidence for antimicrobial and anticancer activity of pituitary adenylate cyclase-activating polypeptide (PACAP) from North African catfish (Clarias gariepinus): Its potential use as novel therapeutic agent in fish and humans

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a regulatory neuropeptide that belongs to the secretin/glucagon superfamily, of which some members have shown antimicrobial activities. Contrasting to mammals, published studies on the action of PACAP in non-mammalian vertebrate immune system remain scarce. Some of our recent studies added this peptide to the growing list of mediators that allow cross-talk between the nervous, endocrine and immune systems in teleost fish. Regulation of PACAP and expression of its receptor genes has been demonstrated during an immune response mounted against acute bacterial infection in fish, though the direct effect of PACAP against fish pathogenic bacteria has never been addressed. Current work provides evidence of antimicrobial activity of Clarias gariepinus PACAP against a wide spectrum of Gram-negative and Gram-positive bacteria and fungi of interest for human medicine and aquaculture, in which computational prediction studies supported the putative PACAP therapeutic activity. Results also indicated that catfish PACAP not only exhibits inhibitory effects on pathogen growth, but also affects the proliferation of human non-small cell lung cancer cell line H460 in a dose-dependent manner. The observed cytotoxic activity of catfish PACAP against human tumor cells and pathogenic microorganisms, but not healthy fish and mammalian erythrocytes support a potential physiological role of this neuropeptide in selective microbial and cancer cell killing. All together, our findings extend the mechanisms by which PACAP could contribute to immune responses, and open up new avenues for future therapeutic application of this bioactive neuropeptide.

Examination of Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) as a Potential Biomarker in Heart Failure Patients

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic and multifunctional neuropeptide having neurotrophic, neuroprotective, and general cytoprotective actions in a variety of tissues based on its anti-apoptotic, anti-inflammatory, and antioxidant effects. Several studies have demonstrated its cardioprotective effects in vitro and in various animal models. However, few data are available on the presence of PACAP in human cardiac tissues and its role in the pathomechanism and progression of different cardiac disorders, particularly heart failure. Earlier, our research group has shown PAC1 receptor immunoreactivity in human heart tissue samples and we have found significantly elevated PACAP27- and PACAP38-like immunoreactivity in ischemic cardiac samples compared to valvular abnormalities with radioimmunoassay. In the last few years, numerous studies examined the presence and the changes of PACAP levels in different human tissue samples and biological fluids to show alterations in different physiological and pathological conditions. Therefore, the aim of the present study was to measure the alterations of blood PACAP levels in chronic heart failure caused by primary dilated cardiomyopathy or ischemic cardiomyopathy and to examine the possible relationship between serum levels of PACAP, N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and systolic left ventricular function, the most reliable biomarkers of heart failure. In the group of mild heart failure patients, a significant strong negative correlation was detected. Furthermore, in moderate heart failure, we found a significant moderate negative correlation between PACAP and NT-proBNP levels only in ischemic subgroup. Positive correlation was found between serum PACAP level and ejection fraction only in patients with heart failure due to ischemic cardiomyopathy but not in patients with primary dilated cardiomyopathy. In summary, remarkable differences were observed between the ischemic and non-ischemic heart failure suggesting that PACAP might play an important role in the pathomechanism and progression of ischemic heart failure and it might be a potential biomarker of cardiac diseases in the future.

Immune response- and viral control-related pathways in the progression of chronic hepatitis B

BACKGROUND

Chronic hepatitis B (CHB) is a complicated and dynamic course, and is associated with advanced liver disease. Host immune response against viral infection plays a pivotal role in the progression of CHB. However, it is still uncharted that how the hepatic transcriptomes in patients with CHB are correlated with the clinical phases.

OBJECTIVE

This study aimed to identify the specific sub-networks across various phases of CHB and infer potential pathways for phenotypic outcome prediction.

METHODS

In this study, we performed the pairwise comparisons of the hepatic transcriptomes of CHB patients under different phases, and constructed the differential co-expression networks (DCNs). We firstly identified the critical genes from each DCN according to the adjacency matrix of the network. Then, the specific sub-networks were digged by iteratively affiliating genes that can increase the classification accuracy, using a snow-ball sampling strategy. Permutation test was implemented to determine the statistical significance of these sub-networks. Finally, each sub-network was given a most significant functional pathway.

RESULTS

We constructed 3 DCNs by pairwise comparing the hepatic transcriptomes among three CHB phases, and systemically tracked 1, 1 and 2 specific sub-networks and pathways, respectively. Relative to immune tolerant phase, TGF-beta receptor signaling in EMT (epithelial to mesenchymal transition) pathway was significantly changed in the immune clearance phase, and nuclear receptor transcription pathway and adenylate cyclase activating pathway were altered in inactive carrier state. The host genes related to DNA strand elongation showed significant difference between the immune clearance phase and inactive carrier state.

CONCLUSIONS

By pairwise comparing the hepatic transcriptomes of CHB patients under a network view, several immune- and viral control-related pathways were identified in this study. These results might serve as a foundation for characterizing the host transcriptomes responded to CHB infection, and hold clues for the development of potential targets for disease control.

Viral and bacterial septicaemic infections modulate the expression of PACAP splicing variants and VIP/PACAP receptors in brown trout immune organs

Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) and PACAP-Related Peptide (PRP) are structurally similar peptides encoded in the same transcripts. Their transcription has been detected not only in the brain but also in a wide range of peripheral tissues, even including organs of the immune system. PACAP exerts pleiotropic activities through G-protein coupled membrane receptors: the PACAP-specific PAC-1 and the VPAC-1 and VPAC-2 receptors that exhibit similar affinities for the Vasoactive Intestinal Peptide (VIP) and PACAP. Recent findings added PACAP and its receptors to the growing list of mediators that allow cross-talk between the nervous, endocrine and immune systems in fish. In this study the expression of genes encoding for PACAP and PRP, as well as VIP/PACAP receptors was studied in laboratory-reared brown trout (Salmo trutta) after septicaemic infections. Respectively Viral Haemorrhagic Septicaemia Virus (VHSV-Ia) or the Gram-negative bacterium Yersinia ruckeri (ser. O1 - biot. 2) were used in infection challenges. Kidney and spleen, the teleost main lymphopoietic organs, were sampled during the first two weeks post-infection. RT-qPCR analysis assessed specific pathogens burden and gene expression levels. PACAP and PRP transcription in each organ was positively correlated to the respective pathogen burden, assessed targeting the VHSV-glycoprotein or Y. ruckeri 16S rRNA. Results showed as the transcription of PACAP splicing variants and VIP/PACAP receptors is modulated in these organs during an acute viral and bacterial septicaemic infections in brown trout. These gene expression results provide clues as to how the PACAP system is modulated in fish, confirming an involvement during active immune responses elicited by both viral and bacterial aetiological agents. However, further experimental evidence is still required to fully elucidate and characterize the role of PACAP and PRP for an efficient immune response against pathogens.