Vasoactive intestinal peptide: a neuropeptide with pleiotropic immune functions

Microglia cells treated with synthetic vasoactive intestinal peptide or transduced with LentiVIP protect neuronal cells against degeneration

A common pathological hallmark of neurodegenerative disorders is neuronal cell death, accompanied by neuroinflammation and oxidative stress. The vasoactive intestinal peptide (VIP) is a pleiotropic peptide that combines neuroprotective and immunomodulatory actions. The gene therapy field shows long-term promise for treating a wide range of neurodegenerative diseases (ND). In this study, we aimed to investigate the in vitro efficacy of transduction of microglia using lentiviral gene therapy vectors encoding VIP (LentiVIP). Additionally, we tested the protective effects of the secretome derived from LentiVIP-infected "immortalized human" microglia HMC3 cells, and cells treated with Synthetic VIP (SynVIP), against toxin-induced neurodegeneration. First, LentiVIP, which stably expresses VIP, was generated and purified. VIP secretion in microglial conditioned media (MG CM) for LentiVIP-infected HMC3 microglia cells was confirmed. Microglia cells were activated with lipopolysaccharide, and groups were formed as follows: 1) Control, 2) SynVIP-treated, or 3) LentiVIP-transduced. These MG CM were applied on an in vitro neurodegenerative model formed by differentiated (d)-SH-SY5Y cells. Then, cell survival analysis and apoptotic nuclear staining, besides measurement of oxidative/inflammatory parameters in CM of cells were performed. Activated MG CM reduced survival rates of both control and toxin-applied (d)-SH-SY5Y cells, whereas LentiVIP-infected MG CM and SynVIP-treated ones exhibited better survival rates. These findings were supported by apoptotic nuclear evaluations of (d)-SH-SY5Y cells, alongside oxidative/inflammatory parameters in their CM. LentiVIP seems worthy of further studies for the treatment of ND because of the potential of gene therapy to treat diseases effectively with a single injection.

Insights into the molecular mechanisms and signalling pathways of epithelial to mesenchymal transition (EMT) in colorectal cancer: A systematic review and bioinformatic analysis of gene expression

Colorectal cancer (CRC) is ranked as the second leading cause of mortality worldwide, mainly due to metastasis. Epithelial to mesenchymal transition (EMT) is a complex cellular process that drives CRC metastasis, regulated by changes in EMT-associated gene expression. However, while numerous genes have been identified as EMT regulators through various in vivo and in vitro studies, little is known about the genes that are differentially expressed in CRC tumour tissue and their signalling pathway in regulating EMT. Using an integration of systematic search and bioinformatic analysis, gene expression profiles of CRC tumour tissues were compared to non-tumour adjacent tissues to identify differentially expressed genes (DEGs), followed by performing systematic review on common identified DEGs. Fifty-eight common DEGs were identified from the analysis of 82 tumour tissue samples obtained from four gene expression datasets (NCBI GEO). These DEGS were then systematically searched for their roles in modulating EMT in CRC based on previously published studies. Following this, 10 common DEGs (CXCL1, CXCL8, MMP1, MMP3, MMP7, TACSTD2, VIP, HPGD, ABCG2, CLCA4) were included in this study and subsequently subjected to further bioinformatic analysis. Their roles and functions in modulating EMT in CRC were discussed in this review. This study enhances our understanding of the molecular mechanisms underlying EMT and uncovers potential candidate genes and pathways that could be targeted in CRC.

Podophyllotoxin-mediated neurotoxicity via the microbiota-gut-brain axis in SD rats based on the toxicological evidence chain (TEC) concept

Podophyllotoxin (PPT) is a naturally occurring aryltetralin lignan. However, its clinical application has been limited due to its neurotoxicity, the mechanism of which remains unclear. This study aimed to investigate the potential involvement of the microbiota-gut-brain (MGB) axis in PPT-induced neurotoxicity using the toxicological evidence chain concept. Our approach included behavioral testing in rats, evaluation of colon and hippocampal pathological changes, examination of proinflammatory factors, brain-gut peptides, and an in-depth analysis of gut microbiome and metabolic profiles. Our results demonstrated that PPT exposure compromised cognitive functions, induced damage to the colon and hippocampus, and increased intestinal permeability in rats. Furthermore, it elevated proinflammatory factors, particularly TNF-α and IL-6, while causing disruptions in the gut microbiota, favoring Escherichia-Shigella over Lactobacillus. Significant alterations in metabolic profiles in feces, serum, and hippocampus, particularly in tryptophan metabolism with a correlation to inflammatory factors and Escherichia-Shigella, were also observed. Our findings suggest that PPT promotes the enrichment of Escherichia-Shigella leading to inflammatory factor production and alterations in kynurenine metabolism in the hippocampus, potentially contributing to neurotoxicity. The study provides novel insights into the mechanistic pathways of PPT-induced neurotoxicity, emphasizing the role of the MGB axis and offering avenues for therapeutic interventions.

Capillary electrophoresis in the analysis of therapeutic peptides-A review

Therapeutic peptides are a growing class of innovative drugs with high efficiency and a low risk of adverse effects. These biomolecules fall within the molecular mass range between that of small molecules and proteins. However, their inherent instability and potential for degradation underscore the importance of reliable and effective analytical methods for pharmaceutical quality control, therapeutic drug monitoring, and compliance testing. Liquid chromatography-mass spectrometry (LC-MS) has long time been the "gold standard" conventional method for peptide analysis, but capillary electrophoresis (CE) is increasingly being recognized as a complementary and, in some cases, superior, highly efficient, green, and cost-effective alternative technique. CE can separate peptides composed of different amino acids owing to differences in their net charge and size, determining their migration behavior in an electric field. This review provides a comprehensive overview of therapeutic peptides that have been used in the clinical environment for the last 25 years. It describes the properties, classification, current trends in development, and clinical use of therapeutic peptides. From the analytical point of view, it discusses the challenges associated with the analysis of therapeutic peptides in pharmaceutical and biological matrices, as well as the evaluation of CE as a whole and the comparison with LC methods. The article also highlights the use of microchip electrophoresis, nonaqueous CE, and nonconventional hydrodynamically closed CE systems and their applications. Overall, the article emphasizes the importance of developing new CE-based analytical methods to ensure the high quality, safety, and efficacy of therapeutic peptides in clinical practice.

Bridging the Mind and Gut: Uncovering the Intricacies of Neurotransmitters, Neuropeptides, and their Influence on Neuropsychiatric Disorders

BACKGROUND

The gut-brain axis (GBA) is a bidirectional signaling channel that facilitates communication between the gastrointestinal tract and the brain. Recent research on the gut-brain axis demonstrates that this connection enables the brain to influence gut function, which in turn influences the brain and its cognitive functioning. It is well established that malfunctioning of this axis adversely affects both systems' ability to operate effectively.

OBJECTIVE

Dysfunctions in the GBA have been associated with disorders of gut motility and permeability, intestinal inflammation, indigestion, constipation, diarrhea, IBS, and IBD, as well as neuropsychiatric and neurodegenerative disorders like depression, anxiety, schizophrenia, autism, Alzheimer's, and Parkinson's disease. Multiple research initiatives have shown that the gut microbiota, in particular, plays a crucial role in the GBA by participating in the regulation of a number of key neurochemicals that are known to have significant effects on the mental and physical well-being of an individual.

METHODS

Several studies have investigated the relationship between neuropsychiatric disorders and imbalances or disturbances in the metabolism of neurochemicals, often leading to concomitant gastrointestinal issues and modifications in gut flora composition. The interaction between neurological diseases and gut microbiota has been a focal point within this research. The novel therapeutic interventions in neuropsychiatric conditions involving interventions such as probiotics, prebiotics, and dietary modifications are outlined in this review.

RESULTS

The findings of multiple studies carried out on mice show that modulating and monitoring gut microbiota can help treat symptoms of such diseases, which raises the possibility of the use of probiotics, prebiotics, and even dietary changes as part of a new treatment strategy for neuropsychiatric disorders and their symptoms.

CONCLUSION

The bidirectional communication between the gut and the brain through the gut-brain axis has revealed profound implications for both gastrointestinal and neurological health. Malfunctions in this axis have been connected to a range of disorders affecting gut function as well as cognitive and neuropsychiatric well-being. The emerging understanding of the role of gut microbiota in regulating key neurochemicals opens up possibilities for novel treatment approaches for conditions like depression, anxiety, and neurodegenerative diseases.

Immunomodulatory role of vasoactive intestinal peptide and ghrelin in Oncorhynchus mykiss

Neuropeptides are a group of peptides derived from precursor proteins synthesized in neuronal and nonneuronal cells. The classical functions of neuropeptides have been extensively studied in mammals, including neuromodulation in the central nervous system, molecular signaling in the peripheral nervous system, and immunomodulation associated mainly with anti-inflammatory activity. In contrast, in teleosts, studies of the immunomodulatory function of these neuropeptides are limited. In Oncorhynchus mykiss, vasoactive intestinal peptide (VIP) mRNA sequences have not been cloned, and the role of VIP in modulating the immune system has not been studied. Furthermore, in relation to other neuropeptides with possible immunomodulatory function, such as ghrelin, there are also few studies. Therefore, in this work, we performed molecular cloning, identification, and phylogenetic analysis of three VIP precursor sequences (prepro-VIP1, VIP2 and VIP3) in rainbow trout. In addition, the immunomodulatory function of both neuropeptides was evaluated in an in vitro model using the VIP1 sequence identified in this work and a ghrelin sequence already studied in O. mykiss. The results suggest that the prepro-VIP2 sequence has the lowest percentage of identity with respect to the other homologous sequences and is more closely related to mammalian orthologous sequences. VIP1 induces significant expression of both pro-inflammatory (IFN-γ, IL-1β) and anti-inflammatory (IL-10 and TGF-β) cytokines, whereas ghrelin only induces significant expression of proinflammatory cytokines such as IL-6 and TNF-α.

Crosstalk of nervous and immune systems in pancreatic cancer

Pancreatic cancer is a highly malignant tumor known for its extremely low survival rate. The combination of genetic disorders within pancreatic cells and the tumor microenvironment contributes to the emergence and progression of this devastating disease. Extensive research has shed light on the nature of the microenvironmental cells surrounding the pancreatic cancer, including peripheral nerves and immune cells. Peripheral nerves release neuropeptides that directly target pancreatic cancer cells in a paracrine manner, while immune cells play a crucial role in eliminating cancer cells that have not evaded the immune response. Recent studies have revealed the intricate interplay between the nervous and immune systems in homeostatic condition as well as in cancer development. In this review, we aim to summarize the function of nerves in pancreatic cancer, emphasizing the significance to investigate the neural-immune crosstalk during the advancement of this malignant cancer.

Heme and Cu2+-induced vasoactive intestinal peptide (VIP) tyrosine nitration: A possible molecular mechanism for the attenuated anti-inflammatory effect of VIP in inflammatory diseases

Vasoactive intestinal peptide (VIP) is a neuropeptide that play an important role in immunoregulation and anti-inflammation. Numerous inflammatory/autoimmune disorders are associated with decreased VIP binding ability to receptors and diminished VIP activation of cAMP generation in immune cells. However, the mechanisms linking oxidative/nitrative stress to VIP immune dysfunction remain unknown. It has been reported that the elevated heme or Cu2+ in inflammatory diseases can cause oxidative and nitrative damage to nearby biological targets under high oxidative stress conditions, which affects the structure and activity of linked peptides or proteins. Thus, the VIP down-regulated immune response may be interfered by redox metal catalyzed VIP tyrosine nitration. To explore this, we systematically investigated the possibility of heme or Cu2+ to catalyze VIP tyrosine nitration. The results showed that Tyr10 and Tyr22 of VIP can both be nitrated in heme/H2O2/NO2- system as well as in Cu2+/H2O2/NO2- system. Then, we used synthetic mutant VIPs with tyrosine residues substituted by 3-nitrotyrosine to study the impact of tyrosine nitration on VIP activity in SHSY-5Y cells. Our findings demonstrated that VIP nitration dramatically decreased the content of its α-helix and random coil, suggesting that VIP nitration might reduce its affinity to the receptor. This was further confirmed in the cAMP assay. The results showed that 10 nM of these tyrosine nitrated VIPs could significantly (p < 0.01) decrease cAMP secretion compared to the wild type VIP. Our data reveal that the attenuation of the neuroprotective effect of VIP in inflammation-related diseases might be attributed to metal-catalyzed VIP tyrosine nitration.

Drastic decline in vasoactive intestinal peptide expression in the suprachiasmatic nucleus in obese mice on a long-term high-fat diet

The suprachiasmatic nucleus (SCN) is the main region for the regulation of circadian rhythms. Although the SCN contains a heterogeneous neurochemical phenotype with a wide variety of neuropeptides, a key role has been suggested for the vasoactive intestinal neuropeptide (VIP) as a modulator circadian, reproductive, and seasonal rhythms. VIP is a 28-amino acid polypeptide hormone that belongs to the secretin-glucagon peptide superfamily and shares 68 % homology with the pituitary adenylate cyclase-activating polypeptide (PACAP). VIP acts as an endogenous appetite inhibitor in the central nervous system, where it participates in the control of appetite and energy homeostasis. In recent years, significant efforts have been made to better understand the role of VIP in the regulation of appetite/satiety and energy balance. This study aimed to elucidate the long-term effect of an obesogenic diet on the distribution and expression pattern of VIP in the SCN and nucleus accumbens (NAc) of C57BL/6 mice. A total of 15 female C57BL/6J mice were used in this study. Female mice were fed ad libitum with water and, either a standard diet (SD) or a high-fat diet (HFD) to induce obesity. There were 7 female mice on the SD and 8 on the HFD. The duration of the experiment was 365 days. The morphological study was performed using immunohistochemistry and double immunofluorescence techniques to study the neurochemical profile of VIP neurons of the SCN of C57BL/6 mice. Our data show that HFD-fed mice gained weight and showed reduced VIP expression in neurons of the SCN and also in fibres located in the NAc. Moreover, we observed a loss of neuropeptide Y (NPY) expression in fibres surrounding the SCN. Our findings on VIP may contribute to the understanding of the pathophysiological mechanisms underlying obesity in regions associated with uncontrolled intake of high-fat foods and the reward system, thus facilitating the identification of novel therapeutic targets.

Biosynthesis and Function of VIP and Oxytocin: Mechanisms of C-terminal Amidation, Oxytocin Secretion and Transport

In this review, we provide the status of research on vasoactive intestinal peptide (VIP) and oxytocin, typical C-terminal α-amidated peptide hormones, including their precursor protein structures, processing and C-terminal α-amidation, and the recently identified mechanisms of regulation of oxytocin secretion and its transportation through the blood brain barrier. More than half of neural and endocrine peptides, such as VIP and oxytocin, have the α-amide structure at their C-terminus, which is essential for biological activities. We have studied the synthesis and function of C-terminal α-amidated peptides, including VIP and oxytocin, since the 1980s. Human VIP mRNA encoded not only VIP but also another related C-terminal α-amidated peptide, PHM-27 (peptide having amino-terminal histidine, carboxy-terminal methionine amide, and 27 amino acid residues). The human VIP/PHM-27 gene is composed of 7 exons and regulated synergistically by cyclic AMP and protein kinase C pathways. VIP has an essential role in glycemic control using transgenic mouse technology. The peptide C-terminal α-amidation proceeded through a 2-step mechanism catalyzed by 2 different enzymes encoded in a single mRNA. In the oxytocin secretion from the hypothalamus/the posterior pituitary, the CD38-cyclic ADP-ribose signal system, which was first established in the insulin secretion from pancreatic β cells of the islets of Langerhans, was found to be essential. A possible mechanism involving RAGE (receptor for advanced glycation end-products) of the oxytocin transportation from the blood stream into the brain through the blood-brain barrier has also been suggested.

PACAP and VIP Neuropeptides' and Receptors' Effects on Appetite, Satiety and Metabolism

The overwhelming increase in the prevalence of obesity and related disorders in recent years is one of the greatest threats to the global healthcare system since it generates immense healthcare costs. As the prevalence of obesity approaches epidemic proportions, the importance of elucidating the mechanisms regulating appetite, satiety, body metabolism, energy balance and adiposity has garnered significant attention. Currently, gastrointestinal (GI) bariatric surgery remains the only approach capable of achieving successful weight loss. Appetite, satiety, feeding behavior, energy intake and expenditure are regulated by central and peripheral neurohormonal mechanisms that have not been fully elucidated yet. Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) and Vasoactive Intestinal Polypeptide (VIP) are members of a family of regulatory peptides that are widely distributed in parallel with their specific receptors, VPAC1R, VPAC2R and PAC1R, in the central nervous system (CNS) and in the periphery, such as in the gastrointestinal tract and its associated organs and immune cells. PACAP and VIP have been reported to play an important role in the regulation of body phenotype, metabolism and homeostatic functions. The purpose of this review is to present recent data on the effects of PACAP, VIP, VPAC1R, VPAC2R and PAC1R on the modulation of appetite, satiety, metabolism, calorie intake and fat accumulation, to evaluate their potential use as therapeutic targets for the treatment of obesity and metabolic syndrome.

Gene Expression Analysis Links Autocrine Vasoactive Intestinal Peptide and ZEB1 in Gastrointestinal Cancers

VIP (vasoactive intestinal peptide) is a 28-amino acid peptide hormone expressed by cancer and the healthy nervous system, digestive tract, cardiovascular, and immune cell tissues. Many cancers express VIP and its surface receptors VPAC1 and VPAC2, but the role of autocrine VIP signaling in cancer as a targetable prognostic and predictive biomarker remains poorly understood. Therefore, we conducted an in silico gene expression analysis to study the mechanisms of autocrine VIP signaling in cancer. VIP expression from TCGA PANCAN tissue samples was analyzed against the expression levels of 760 cancer-associated genes. Of the 760 genes, 10 (MAPK3, ZEB1, TEK, NOS2, PTCH1 EIF4G1, GMPS, CDK2, RUVBL1, and TIMELESS) showed statistically meaningful associations with the VIP (Pearson's R-coefficient > |0.3|; p < 0.05) across all cancer histologies. The strongest association with the VIP was for the epithelial-mesenchymal transition regulator ZEB1 in gastrointestinal malignancies. Similar positive correlations between the VIP and ZEB1 expression were also observed in healthy gastrointestinal tissues. Gene set analysis indicates the VIP is involved in the EMT and cell cycle pathways, and a high VIP and ZEB1 expression is associated with higher median estimate and stromal scores These findings uncover novel mechanisms for VIP- signaling in cancer and specifically suggest a role for VIP as a biomarker of ZEB1-mediated EMT. Further studies are warranted to characterize the specific mechanism of this interaction.

The magic of small-molecule drugs during ex vivo expansion in adoptive cell therapy

In the past decades, advances in the use of adoptive cellular therapy to treat cancer have led to unprecedented responses in patients with relapsed/refractory or late-stage malignancies. However, cellular exhaustion and senescence limit the efficacy of FDA-approved T-cell therapies in patients with hematologic malignancies and the widespread application of this approach in treating patients with solid tumors. Investigators are addressing the current obstacles by focusing on the manufacturing process of effector T cells, including engineering approaches and ex vivo expansion strategies to regulate T-cell differentiation. Here we reviewed the current small-molecule strategies to enhance T-cell expansion, persistence, and functionality during ex vivo manufacturing. We further discussed the synergistic benefits of the dual-targeting approaches and proposed novel vasoactive intestinal peptide receptor antagonists (VIPR-ANT) peptides as emerging candidates to enhance cell-based immunotherapy.

Research on the mechanism of prednisone in the treatment of ITP via VIP/PACAP-mediated intestinal immune dysfunction

RATIONALE

Immune thrombocytopenia (ITP) is thought to be a result of immune dysfunction, which is treated by glucocorticoids such as prednisone. Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) have immunomodulatory properties, but their role in intestinal immune control is unclear. The major goal of this study was to look at the effects of prednisone on platelet, VIP, and PACAP levels in ITP mice, as well as the regulatory system that controls intestinal immunity.

METHODS

Eighteen BALB/c mice were randomly divided into three groups: blank control group, model control group, and prednisone group, with six mice in each group. The ITP animal model control group and the prednisone group were injected with anti-platelet serum (APS) to replicate the ITP animal model. The prednisone group began prednisone intervention on the 8th day. Platelet count was dynamically measured before APS injection, on the 4th day of injection, on the 1st day of administration, on the 4th day of administration, and at the end of the experiment. After the experiment, the expression of p53 protein in mouse mesenteric lymph node lymphocytes was detected by immunohistochemistry. The changes in lymphocyte apoptosis rate in mouse mesenteric lymph nodes were detected by in situ terminal transferase labeling (TUNEL). The contents of VIP and PACAP in the mouse brain, colon, and serum were detected by enzyme-linked immunosorbent assay (ELISA). The contents of IFN-γ, IL-4, IL-10, IL-17A in the mouse spleen were detected by ELISA.

RESULTS

①Changes of peripheral platelet count: there was no significant difference in platelet count among the three groups before modeling; on the 4th day, the platelet count decreased in the model control group and prednisone group; on the 8th day, the number of platelets in model control group and prednisone group was at the lowest level; on the 12th day, the platelet count in prednisone group recovered significantly; on the 15th day, the platelet count in prednisone group continued to rise. ②Changes of VIP, PACAP: compared with the blank control group, VIP and PACAP in the model control group decreased significantly in the brain, colon, and serum. Compared with the model control group, the levels of VIP and PACAP in the brain, colon, and serum in the prednisone group were increased except for serum PACAP. ③Changes of mesenteric lymphocytes: the expression of p53 protein in the mesenteric lymph nodes of model control group mice was significantly higher than that of blank control group mice. After prednisone intervention, the expression of p53 protein decreased significantly.④Changes of cytokines in spleen: compared with blank control group, IFN- γ, IL-17A increased and IL-4 and IL-10 decreased in model control group. After prednisone intervention, IFN- γ, IL-17A was down-regulated and IL-4 and IL-10 were upregulated.

CONCLUSIONS

Prednisone-upregulated VIP and PACAP levels decreased P53 protein expression and apoptosis rate in mesenteric lymph node lymphocytes and affected cytokine expression in ITP model mice. Therefore, we speculate that the regulation of intestinal immune function may be a potential mechanism of prednisone in treating ITP.

Vasoactive intestinal peptide blockade suppresses tumor growth by regulating macrophage polarization and function in CT26 tumor-bearing mice

Macrophages are a major population of immune cells in solid cancers, especially colorectal cancers. Tumor-associated macrophages (TAMs) are commonly divided into M1-like (tumor suppression) and M2-like (tumor promotion) phenotypes. Vasoactive intestinal peptide (VIP) is an immunoregulatory neuropeptide with a potent anti-inflammatory function. Inhibition of VIP signaling has been shown to increase CD8⁺ T cell proliferation and function in viral infection and lymphoma. However, the role of VIP in macrophage polarization and function in solid tumors remains unknown. Here, we demonstrated that conditioned medium from CT26 (CT26-CM) cells enhanced M2-related marker and VIP receptor (VPAC) gene expression in RAW264.7 macrophages. VIP hybrid, a VIP antagonist, enhanced M1-related genes but reduced Mrc1 gene expression and increased phagocytic ability in CT26-CM-treated RAW264.7 cells. In immunodeficient SCID mice, VIP antagonist alone or in combination with anti-PD-1 antibody attenuated CT26 tumor growth compared with the control. Analysis of tumor-infiltrating leukocytes found that VIP antagonist increased M1/M2 ratios and macrophage phagocytosis of CT26-GFP cells. Furthermore, Vipr2 gene silencing or VPAC2 activation affected the polarization of CT26-CM-treated RAW264.7 cells. In conclusion, the inhibition of VIP signaling enhanced M1 macrophage polarization and macrophage phagocytic function, resulting in tumor regression in a CT26 colon cancer model.

The effect of acupuncture on pain and swelling of arthritis animal models: A systematic review and meta-analysis

Arthritis, the inflammation of joints, attributes to the patient's pain, joint deformation, and limited range of motion. Emerging studies have shown the effects of acupuncture on different types of arthritis. We aimed to assess the effects of acupuncture on arthritis animal models and summarize the related mechanisms. We retrieved studies that met our criteria from PubMed, MEDLINE, EMBASE and the Research Information Service System. The quality assessment was evaluated by using the Systematic Review Centre for Laboratory Animal Experimentation's risk of bias tool. The pain withdrawal latency, pain withdrawal threshold, and paw volume data were digitized using Engauge Digitizer software. The meta-analysis was performed, and the figures were generated using RevMan software. The meta-analysis of data from 21 animal studies revealed that acupuncture increased tolerance to pain stimuli, and reduced swelling in arthritis animals. Although the number of included studies is insufficient, the results suggest acupuncture to be effective in improving arthritis-induced inflammation and pain by regulating the nervous and immune system.

Targeting vasoactive intestinal peptide-mediated signaling enhances response to immune checkpoint therapy in pancreatic ductal adenocarcinoma

A paucity of effector T cells within tumors renders pancreatic ductal adenocarcinoma (PDAC) resistant to immune checkpoint therapies. While several under-development approaches target immune-suppressive cells in the tumor microenvironment, there is less focus on improving T cell function. Here we show that inhibiting vasoactive intestinal peptide receptor (VIP-R) signaling enhances anti-tumor immunity in murine PDAC models. In silico data mining and immunohistochemistry analysis of primary tumors indicate overexpression of the neuropeptide vasoactive intestinal peptide (VIP) in human PDAC tumors. Elevated VIP levels are also present in PDAC patient plasma and supernatants of cultured PDAC cells. Furthermore, T cells up-regulate VIP receptors after activation, identifying the VIP signaling pathway as a potential target to enhance T cell function. In mouse PDAC models, VIP-R antagonist peptides synergize with anti-PD-1 antibody treatment in improving T cell recruitment into the tumors, activation of tumor-antigen-specific T cells, and inhibition of T cell exhaustion. In contrast to the limited single-agent activity of anti-PD1 antibodies or VIP-R antagonist peptides, combining both therapies eliminate tumors in up to 40% of animals. Furthermore, tumor-free mice resist tumor re-challenge, indicating anti-cancer immunological memory generation. VIP-R signaling thus represents a tumor-protective immune-modulatory pathway that is targetable in PDAC.

Donor plasmacytoid dendritic cells limit graft-versus-host disease through vasoactive intestinal polypeptide expression

Vasoactive intestinal polypeptide (VIP), an anti-inflammatory neuropeptide with pleiotropic cardiovascular effects, induces differentiation of hematopoietic stem cells into regulatory dendritic cells that limit graft-versus-host disease (GVHD) in allogeneic hematopoietic stem cell transplant (HSCT) recipients. We have previously shown that donor plasmacytoid dendritic cells (pDCs) in bone marrow (BM) donor grafts limit the pathogenesis of GVHD. In this current study we show that murine and human pDCs express VIP, and that VIP-expressing pDCs limit T-cell activation and expansion using both in vivo and in vitro model systems. Using T cells or pDCs from transgenic luciferase+ donors in murine bone marrow transplantation (BMT), we show similar homing patterns of donor pDCs and T cells to the major sites for alloactivation of donor T cells: spleen and gut. Cotransplanting VIP-knockout (KO) pDCs with hematopoietic stem cells and T cells in major histocompatibility complex mismatched allogeneic BMT led to lower survival, higher GVHD scores, and more colon crypt cell apoptosis than transplanting wild-type pDCs. BMT recipients of VIP-KO pDCs had more T helper 1 polarized T cells, and higher plasma levels of granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-α than recipients of wild-type pDCs. T cells from VIP-KO pDC recipients had increasing levels of bhlhe40 transcripts during the first 2 weeks posttransplant, and higher levels of CyclophilinA/Ppia transcripts at day 15 compared with T cells from recipients of wild-type pDCs. Collectively, these data indicate paracrine VIP synthesis by donor pDCs limits pathogenic T-cell inflammation, supporting a novel mechanism by which donor immune cells regulate T-cell activation and GVHD in allogeneic BMT.

Sympathetic activation leads to Schlemm's canal expansion via increasing vasoactive intestinal polypeptide secretion from trabecular meshwork

We previously demonstrated vasoactive intestinal polypeptide (VIP) eyedrops reduce intraocular pressure (IOP) and stabilize cytoskeleton of the Schlemm's canal (SC) endothelium in a chronic ocular hypertension rat model. Here we determine if the trabecular meshwork (TM) releases endogenous VIP and affect SC in paracrine manner, and whether this cellular interaction via VIP is strengthened under stimulated sympathetic activity. A rat model of moderate-intensity exercise was established to stimulate sympathetic activation. IOP post exercise was measured by a rebound tonometer. Sympathetic nerve activity at the TM was immunofluorescence-stained with DβH and PGP9.5. Morphological changes of TM and SC were quantitatively measured by hematoxylin-eosin (HE) staining. Further, epinephrine was applied to mimic sympathetic excitation on primary rat TM cells, and ELISA to measure VIP levels in the medium. The cytoskeleton protective effect of VIP in the epinephrine-stimulated conditioned medium (Epi-CM) was evaluated in oxidative stressed human umbilical vein endothelial cells (HUVECs). Elevated sympathetic nerve activity was found at TM post exercise. Changes accompanying the sympathetic excitation included thinned TM, expanded SC and decreased IOP, which were consistent with epinephrine treatment. Epinephrine decreased TM cell size, enhanced VIP expression and release in the medium in vitro. Epi-CM restored linear F-actin and cell junction integrity in H₂O₂ treated HUVECs. Blockage of VIP receptor by PG99-465 attenuated the protective capability of Epi-CM. VIP expression was upregulated at TM and the inner wall of SC post exercise in vivo. PG99-465 significantly attenuated exercise-induced SC expansion and IOP reduction. Thus, the sympathetic activation promoted VIP release from TM cells and subsequently expanded SC via stabilizing cytoskeleton, which resulted in IOP reduction.

Targeting VIP and PACAP Receptor Signaling: New Insights into Designing Drugs for the PACAP Subfamily of Receptors

Pituitary Adenylate Cyclase-Activating Peptide (PACAP) and Vasoactive Intestinal Peptide (VIP) are neuropeptides involved in a diverse array of physiological and pathological processes through activating the PACAP subfamily of class B1 G protein-coupled receptors (GPCRs): VIP receptor 1 (VPAC1R), VIP receptor 2 (VPAC2R), and PACAP type I receptor (PAC1R). VIP and PACAP share nearly 70% amino acid sequence identity, while their receptors PAC1R, VPAC1R, and VPAC2R share 60% homology in the transmembrane regions of the receptor. PACAP binds with high affinity to all three receptors, while VIP binds with high affinity to VPAC1R and VPAC2R, and has a thousand-fold lower affinity for PAC1R compared to PACAP. Due to the wide distribution of VIP and PACAP receptors in the body, potential therapeutic applications of drugs targeting these receptors, as well as expected undesired side effects, are numerous. Designing selective therapeutics targeting these receptors remains challenging due to their structural similarities. This review discusses recent discoveries on the molecular mechanisms involved in the selectivity and signaling of the PACAP subfamily of receptors, and future considerations for therapeutic targeting.

The Role of Chicken Prolactin, Growth Hormone and Their Receptors in the Immune System

Prolactin (PRL) and growth hormone (GH) exhibit important roles in the immune system maintenance. In poultry, PRL mainly plays its roles in nesting, hatching, and reproduction, while GH is primarily responding to body weight, fat formation and feed conversion. In this review, we attempt to provide a critical overview of the relationship between PRL and GH, PRLR and GHR, and the immune response of poultry. We also propose a hypothesis that PRL, GH and their receptors might be used by viruses as viral receptors. This may provide new insights into the pathogenesis of viral infection and host immune response.

Roles of gastrointestinal polypeptides in intestinal barrier regulation

The intestinal barrier is a dynamic entity that is organized as a multilayer system and includes various intracellular and extracellular elements. The gut barrier functions in a coordinated manner to impede the passage of antigens, toxins, and microbiome components and simultaneously preserves the balanced development of the epithelial barrier and the immune system and the acquisition of tolerance to dietary antigens and intestinal pathogens.Numerous scientific studies have shown a significant association between gut barrier damage and gastrointestinal and extraintestinal diseases such as inflammatory bowel disease, celiac disease and hepatic fibrosis. Various internal and external factors regulate the intestinal barrier. Gastrointestinal peptides originate from enteroendocrine cells in the luminal digestive tract and are critical gut barrier regulators. Recent studies have demonstrated that gastrointestinal peptides have a therapeutic effect on digestive tract diseases, enhancing epithelial barrier activity and restoring the gut barrier. This review demonstrates the roles and mechanisms of gastrointestinal polypeptides, especially somatostatin (SST) and vasoactive intestinal peptide (VIP), in intestinal barrier regulation.

The VIP/VPAC1R Pathway Regulates Energy and Glucose Homeostasis by Modulating GLP-1, Glucagon, Leptin and PYY Levels in Mice

Simple Summary

The current study is the first complete characterization of the phenotypic, metabolic, calorimetric, and homeostatic effects of VPAC1R in a null murine model. To evaluate the role of VPAC1R on body phenotype, feeding behavior, glucose/energy homeostasis, metabolic rate and plasma hormones, a long-term study was conducted in VPAC1R^−/− and WT mice. The outcome data document that VPAC1R^−/− mice have altered metabolism and insulin intolerance, with significant increase of feeding bouts, reduction of total energy expenditure and respiratory gases during both the dark and light cycle, together with elevated fasting levels of GLP-1 and PYY, and higher postprandial levels of GLP-1, glucagon leptin and PYY. These findings suggests that VPAC1R controls glucose homeostasis and energy balance by regulating plasma metabolic hormones.

Abstract

Vasoactive Intestinal Peptide binds with high affinity to VPAC1R and VPAC2R, thus regulating key physiologic functions. Previously, we documented in VIP^−/− mice a leaner body phenotype and altered metabolic hormones. Past reports described in VPAC2^−/− mice impaired circadian rhythm, reduced food intake, and altered metabolism. To better define the effects of VPAC1R on body phenotype, energy/glucose homeostasis, and metabolism, we conducted a 12-week study in a VPAC1R null model. Our results reveal that VPAC1^−/− mice experienced significant metabolic alterations during the dark cycle with greater numbers of feeding bouts (p = 0.009), lower Total Energy Expenditure (p = 0.025), VO₂ (p = 0.029), and VCO₂ (p = 0.016); as well as during the light cycle with lower Total Energy Expenditure (p = 0.04), VO₂ (p = 0.044), and VCO₂ (p = 0.029). Furthermore, VPAC1^−/− mice had significantly higher levels of GLP-1 and PYY during fasting, and higher levels of GLP-1, glucagon leptin and PYY during postprandial conditions. In addition, VPAC1^−/− mice had lower levels of glucose at 60′ and 120′, as assessed by insulin tolerance test. In conclusion, this study supports a key role for VPAC1R in the regulation of body glucose/energy homeostasis and metabolism.

An Experimental Model of Neuro-Immune Interactions in the Eye: Corneal Sensory Nerves and Resident Dendritic Cells

The cornea is an avascular connective tissue that is crucial, not only as the primary barrier of the eye but also as a proper transparent refractive structure. Corneal transparency is necessary for vision and is the result of several factors, including its highly organized structure, the physiology of its few cellular components, the lack of myelinated nerves (although it is extremely innervated), the tightly controlled hydration state, and the absence of blood and lymphatic vessels in healthy conditions, among others. The avascular, immune-privileged tissue of the cornea is an ideal model to study the interactions between its well-characterized and dense sensory nerves (easily accessible for both focal electrophysiological recording and morphological studies) and the low number of resident immune cell types, distinguished from those cells migrating from blood vessels. This paper presents an overview of the corneal structure and innervation, the resident dendritic cell (DC) subpopulations present in the cornea, their distribution in relation to corneal nerves, and their role in ocular inflammatory diseases. A mouse model in which sensory axons are constitutively labeled with tdTomato and DCs with green fluorescent protein (GFP) allows further analysis of the neuro-immune crosstalk under inflammatory and steady-state conditions of the eye.

Cerebrospinal fluid and venous biomarkers of shunt-responsive idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis

BACKGROUND

Idiopathic normal pressure hydrocephalus (iNPH) is a neurodegenerative disease and dementia subtype involving disturbed cerebrospinal fluid (CSF) homeostasis. Patients with iNPH may improve clinically following CSF diversion through shunt surgery, but it remains a challenge to predict which patients respond to shunting. It has been proposed that CSF and blood biomarkers may be used to predict shunt response in iNPH.

OBJECTIVE

To conduct a systematic review and meta-analysis to identify which CSF and venous biomarkers predict shunt-responsive iNPH most accurately.

METHODS

Original studies that investigate the use of CSF and venous biomarkers to predict shunt response were searched using the following databases: Embase, MEDLINE, Scopus, PubMed, Google Scholar, and JSTOR. Included studies were assessed using the ROBINS-I tool, and eligible studies were evaluated utilising univariate meta-analyses.

RESULTS

The study included 13 studies; seven addressed lumbar CSF levels of amyloid-β 1-42, nine studies CSF levels of Total-Tau, six studies CSF levels of Phosphorylated-Tau, and seven studies miscellaneous biomarkers, proteomics, and genotyping. A meta-analysis of six eligible studies conducted for amyloid-β 1-42, Total-Tau, and Phosphorylated-Tau demonstrated significantly increased lumbar CSF Phosphorylated-Tau (- 0.55 SMD, p = 0.04) and Total-Tau (- 0.50 SMD, p = 0.02) in shunt-non-responsive iNPH, though no differences were seen between shunt responders and non-responders for amyloid-β 1-42 (- 0.26 SMD, p = 0.55) or the other included biomarkers.

CONCLUSION

This meta-analysis found that lumbar CSF levels of Phosphorylated-Tau and Total-Tau are significantly increased in shunt non-responsive iNPH compared to shunt-responsive iNPH. The other biomarkers, including amyloid-β 1-42, did not significantly differentiate shunt-responsive from shunt-non-responsive iNPH. More studies on the Tau proteins examining sensitivity and specificity at different cut-off levels are needed for a robust analysis of the diagnostic efficiency of the Tau proteins.

Tear film and ocular surface neuropeptides: Characteristics, synthesis, signaling and implications for ocular surface and systemic diseases

Ocular surface neuropeptides are vital molecules primarily involved in maintaining ocular surface integrity and homeostasis. They also serve as communication channels between the nervous system and the immune system, maintaining the homeostasis of the ocular surface. Tear film and ocular surface neuropeptides have a role in disease often due to abnormalities in their synthesis (either high or low production), signaling through defective receptors, or both. This creates imbalances in otherwise normal physiological processes. They have been observed to be altered in many ocular surface and systemic diseases including dry eye disease, ocular allergy, keratoconus, LASIK-induced dry eye, pterygium, neurotrophic keratitis, corneal graft rejection, microbial keratitis, headaches and diabetes. This review examines the characteristics of neuropeptides, their synthesis and their signaling through G-protein coupled receptors. The review also explores the types of neuropeptides within the tears and ocular surface, and how they change in ocular and systemic diseases.

Therapeutic potential of vasoactive intestinal peptide and its receptor VPAC2 in type 2 diabetes

Owing to the increasing prevalence of type 2 diabetes, the development of novel hypoglycemic drugs has become a research hotspot, with the ultimate goal of developing therapeutic drugs that stimulate glucose-induced insulin secretion without inducing hypoglycemia. Vasoactive intestinal peptide (VIP), a 28-amino-acid peptide, can stimulate glucose-dependent insulin secretion, particularly by binding to VPAC2 receptors. VIP also promotes islet β-cell proliferation through the forkhead box M1 pathway, but the specific molecular mechanism remains to be studied. The clinical application of VIP is limited because of its short half-life and wide distribution in the human body. Based on the binding properties of VIP and VPAC2 receptors, VPAC2-selective agonists have been developed to serve as novel hypoglycemic drugs. This review summarizes the physiological significance of VIP in glucose homeostasis and the potential therapeutic value of VPAC2-selective agonists in type 2 diabetes.

Modified BuShenYiQi formula alleviates experimental allergic asthma in mice by negative regulation of type 2 innate lymphoid cells and CD4+ type 9 helper T cells and the VIP-VPAC2 signalling pathway

CONTEXT

Modified BuShenYiQi formula (M-BYF) is derived from BuShenYiQi formula, used for the treatment of allergic asthma. The exact effect and mechanism of M-BYF on the improvement of asthma remain unclear.

OBJECTIVE

We investigated the mechanism underlying the therapeutic effect of M-BYF on allergic asthma.

MATERIALS AND METHODS

The asthma model was established in female BALB/c mice that were sensitized and challenged with ovalbumin (OVA). Mice in the treated groups were orally treated once a day with M-BYF (7, 14 and 28 g/kg/d) or dexamethasone before OVA challenge. Control and Model group received saline. Pathophysiological abnormalities and percentages of lung type 2 innate lymphoid cells (ILC2s) and Th9 cells were measured. Expression levels of type 2 cytokines and transcription factors required for these cells function and differentiation were analysed. Expression of vasoactive intestinal polypeptide (VIP)-VPAC2 signalling pathway-related proteins, and percentages of VIP expressing (VIP⁺) cells and VPAC2, CD90 co-expressing (VPAC2⁺CD90⁺) cells were detected.

RESULTS

M-BYF alleviated airway hyperresponsiveness, inflammation, mucus hypersecretion and collagen deposition in asthmatic mice. M-BYF down-regulated percentages of ILC2s and Th9 cells with lower expression of GATA3, PU.1 and IRF4, reduced IL-5, IL-13, IL-9 and VIP production. The decrease in the expression of VIP-VPAC2 signalling pathway and percentages of VIP⁺ cells, VPAC2⁺CD90⁺ cells were observed after M-BYF treatment. The LD₅₀ value of M-BYF was higher than 90 g/kg.

DISCUSSION AND CONCLUSIONS

M-BYF alleviated experimental asthma by negatively regulating ILC2s and Th9 cells and the VIP-VPAC2 signalling pathway. These findings provide the theoretical basis for future research of M-BYF in asthma patient population.

Tissue-Specific Molecular Markers and Heterogeneity in Type 2 Innate Lymphoid Cells

Innate lymphoid cells (ILCs) are the most recently described group of lymphoid subpopulations. These tissue-resident cells display a heterogeneity resembling that observed on different groups of T cells, hence their categorization as cytotoxic NK cells and helper ILCs type 1, 2 and 3. Each one of these groups is highly diverse and expresses different markers in a context-dependent manner. Type 2 innate lymphoid cells (ILC2s) are activated in response to helminth parasites and regulate the immune response. They are involved in the etiology of diseases associated with allergic responses as well as in the maintenance of tissue homeostasis. Markers associated with their identification differ depending on the tissue and model used, making the study and understanding of these cells a cumbersome task. This review compiles evidence for the heterogeneity of ILC2s as well as discussion and analyses of molecular markers associated with their identity, function, tissue-dependent expression, and how these markers contribute to the interaction of ILC2s with specific microenvironments to maintain homeostasis or respond to pathogenic challenges.

Altered interaction between enteric glial cells and mast cells in the colon of women with irritable bowel syndrome

BACKGROUND

Enteric glial cells (EGC) and mast cells (MC) are intimately associated with gastrointestinal physiological functions. We aimed to investigate EGC-MC interaction in irritable bowel syndrome (IBS), a gut-brain disorder linked to increased intestinal permeability, and MC.

METHODS

Parallel approaches were used to quantify EGC markers in colonic biopsies from healthy controls (HC) and patients with IBS. Data were correlated with MC, vasoactive intestinal polypeptide (VIP) and VIP receptors (VPAC1/VPAC2) expressions, and bacterial translocation through biopsies mounted in Ussing chambers. In addition, we investigated the effects of EGC mediators on colonic permeability and the pharmacological-induced responses of EGC and MC cell lines.

KEY RESULTS

Immunofluorescence of IBS colonic mucosa, as well as Western blotting and ELISA of IBS biopsy lysates, revealed increased glial fibrillary intermediate filament (GFAP) expression, indicating EGC activation. Mucosal GFAP correlated with increased MC and VPAC1⁺ MC numbers and decreased VIP⁺ MC, which seemed to control bacterial translocation in HC. In the contrary, EGC activation in IBS correlated with less MC and VPAC1⁺ MC numbers, and more VIP⁺ MC. In vitro, MC and EGC cell lines showed intracellular calcium responses to each other's mediators. Furthermore, EGC mediators prevented VIP-induced MC degranulation, while MC mediators induced a reactive EGC phenotype. In Ussing chambers, EGC mediators decreased paracellular passage through healthy colonic biopsies.

CONCLUSIONS & INFERENCES

Findings suggest the involvement of EGC and MC in the control of barrier function in the human colon and indicate a potential EGC-MC interaction that seems altered in IBS, with detrimental consequences to colonic permeability. Altogether, results suggest that imbalanced EGC-MC communication contributes to the pathophysiology of IBS.

Vasoactive intestinal peptide promotes host defense against enteric pathogens by modulating the recruitment of group 3 innate lymphoid cells

Group 3 innate lymphoid cells (ILC3s) control the formation of intestinal lymphoid tissues and play key roles in intestinal defense. They express neuropeptide vasoactive intestinal peptide (VIP) receptor 2 (VPAC2), through which VIP modulates their function, but whether VIP exerts other effects on ILC3 remains unclear. We show that VIP promotes ILC3 recruitment to the intestine through VPAC1 independent of the microbiota or adaptive immunity. VIP is also required for postnatal formation of lymphoid tissues as well as the maintenance of local populations of retinoic acid (RA)-producing dendritic cells, with RA up-regulating gut-homing receptor CCR9 expression by ILC3s. Correspondingly, mice deficient in VIP or VPAC1 suffer a paucity of intestinal ILC3s along with impaired production of the cytokine IL-22, rendering them highly susceptible to the enteric pathogen Citrobacter rodentium This heightened susceptibility to C. rodentium infection was ameliorated by RA supplementation, adoptive transfer of ILC3s, or by recombinant IL-22. Thus, VIP regulates the recruitment of intestinal ILC3s and formation of postnatal intestinal lymphoid tissues, offering protection against enteric pathogens.

The Role of Neuropeptides in Pathogenesis of Dry Dye

Neuropeptides are known as important mediators between the nervous and immune systems. Recently, the role of the corneal nerve in the pathogenesis of various ocular surface diseases, including dry eye disease, has been highlighted. Neuropeptides are thought to be important factors in the pathogenesis of dry eye disease, as suggested by the well-known role between the nervous and immune systems, and several recently published studies have elucidated the previously unknown pathogenic mechanisms involved in the role of the neuropeptides secreted from the corneal nerves in dry eye disease. Here, we reviewed the emerging concept of neurogenic inflammation as one of the pathogenic mechanisms of dry eye disease, the recent results of related studies, and the direction of future research.

Neuropeptides of the human magnocellular hypothalamus

Hypothalamic magnocellular nuclei with their large secretory neurons are unique and phylogenetically conserved brain structures involved in the continual regulation of important homeostatic and autonomous functions in vertebrate species. Both canonical and newly identified neuropeptides have a broad spectrum of physiological activity at the hypothalamic neuronal circuit level located within the supraoptic (SON) and paraventricular (PVN) nuclei. Magnocellular neurons express a variety of receptors for neuropeptides and neurotransmitters and therefore receive numerous excitatory and inhibitory inputs from important subcortical neural areas such as limbic and brainstem populations. These unique cells are also densely innervated by axons from other hypothalamic nuclei. The vast majority of neurochemical maps pertain to animal models, mainly the rodent hypothalamus, however accumulating preliminary anatomical structural studies have revealed the presence and distribution of several neuropeptides in the human magnocellular nuclei. This review presents a novel and comprehensive evidence based evaluation of neuropeptide expression in the human SON and PVN. Collectively this review aims to cast a new, medically oriented light on hypothalamic neuroanatomy and contribute to a better understanding of the mechanisms responsible for neuropeptide-related physiology and the nature of possible neuroendocrinal interactions between local regulatory pathways.

Protocatechuic acid influences immune-metabolic changes in the adipose tissue of pregnant women with gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is associated with immune metabolic changes that increase women's risk of developing metabolic disorders later in life. Nutritional intervention is a crucial component in reducing the burden of these pathological features. We examined whether protocatechuic acid (PCA), a major metabolite of anthocyanins abundant in plant food, is able to exert insulin-mimetic activity and modulate inflammation in the visceral adipose tissue (VAT) obtained at delivery, from pregnant women with GDM or normal glucose tolerance (NGT). PCA stimulated glucose uptake in the VAT from both GDM and NGT women. This capability was associated with increased phosphorylation of p38 mitogen-activated protein kinase (p38MAPK), as further demonstrated by the inhibitory effect of SB203580, a p38MAPK inhibitor, on PCA-induced glucose uptake. The GDM-VAT expressed lower adiponectin levels and PCA stimulated adiponectin release in the NGT-VAT and, albeit to a lower extent, in the GDM-VAT. Higher levels of IL6 and TNFα were secreted by the GDM-VAT compared with the NGT one, and PCA had no effects on them. PCA reduced the overexpression of vasoactive intestinal peptide receptor 2 (VPAC2) in the GDM-VAT. Further studies are needed to establish whether and how anthocyanins and food rich in these compounds may contribute to prevent or delay metabolic disorders in women with GDM.

Proteomic Analysis of Synovial Fibroblasts and Articular Chondrocytes Co-Cultures Reveals Valuable VIP-Modulated Inflammatory and Degradative Proteins in Osteoarthritis

Osteoarthritis (OA) is the most common musculoskeletal disorder causing a great disability and a reduction in the quality of life. In OA, articular chondrocytes (AC) and synovial fibroblasts (SF) release innate-derived immune mediators that initiate and perpetuate inflammation, inducing cartilage extracellular matrix (ECM) degradation. Given the lack of therapies for the treatment of OA, in this study, we explore biomarkers that enable the development of new therapeutical approaches. We analyze the set of secreted proteins in AC and SF co-cultures by stable isotope labeling with amino acids (SILAC). We describe, for the first time, 115 proteins detected in SF-AC co-cultures stimulated by fibronectin fragments (Fn-fs). We also study the role of the vasoactive intestinal peptide (VIP) in this secretome, providing new proteins involved in the main events of OA, confirmed by ELISA and multiplex analyses. VIP decreases proteins involved in the inflammatory process (CHI3L1, PTX3), complement activation (C1r, C3), and cartilage ECM degradation (DCN, CTSB and MMP2), key events in the initiation and progression of OA. Our results support the anti-inflammatory and anti-catabolic properties of VIP in rheumatic diseases and provide potential new targets for OA treatment.

Implications of VIP and PACAP in Parkinson's Disease: What do we Know So Far?

BACKGROUND

Parkinson's disease is one of the most common neurodegenerative disorders and although its aetiology is not yet fully understood, neuroinflammation has been identified as a key factor in the progression of the disease. Vasoactive intestinal peptide and pituitary adenylate-cyclase activating polypeptide are two neuropeptides that exhibit anti-inflammatory and neuroprotective properties, modulating the production of cytokines and chemokines and the behaviour of immune cells. However, the role of chemokines and cytokines modulated by the endogenous receptors of the peptides varies according to the stage of the disease.

METHODS

We present an overview of the relationship between some cytokines and chemokines with vasoactive intestinal peptide, pituitary adenylate cyclase activating polypeptide and their endogenous receptors in the context of Parkinson's disease neuroinflammation and oxidative stress, as well as the modulation of microglial cells by the peptides in this context.

RESULTS

The two peptides exhibit neuroprotective and anti-inflammatory properties in models of Parkinson's disease, as they ameliorate cognitive functions, decrease the level of neuroinflammation and promote dopaminergic neuronal survival. The peptides have been tested in a variety of in vivo and in vitro models of Parkinson's disease, demonstrating the potential for therapeutic application.

CONCLUSION

More studies are needed to establish the clinical use of vasoactive intestinal peptide and pituitary adenylate cyclase activating polypeptide as safe candidates for treating Parkinson's disease, as the use of the peptides in different stages of the disease could produce different results concerning effectiveness.

Neuroendocrine Factors in Melanoma Pathogenesis

Simple Summary

Melanoma is a very aggressive and fatal malignant tumor. While curable if diagnosed in its early stages, advanced melanoma, despite the complex therapeutic approaches, is associated with one of the highest mortality rates. Hence, more and more studies have focused on mechanisms that may contribute to melanoma development and progression. Various studies suggest a role played by neuroendocrine factors which can act directly on tumor cells, modulating their proliferation and metastasis capability, or indirectly through immune or inflammatory processes that impact disease progression. However, there are still multiple areas to explore and numerous unknown features to uncover. A detailed exploration of the mechanisms by which neuroendocrine factors can influence the clinical course of the disease could open up new areas of biomedical research and may lead to the development of new therapeutic approaches in melanoma.

Abstract

Melanoma is one of the most aggressive skin cancers with a sharp rise in incidence in the last decades, especially in young people. Recognized as a significant public health issue, melanoma is studied with increasing interest as new discoveries in molecular signaling and receptor modulation unlock innovative treatment options. Stress exposure is recognized as an important component in the immune-inflammatory interplay that can alter the progression of melanoma by regulating the release of neuroendocrine factors. Various neurotransmitters, such as catecholamines, glutamate, serotonin, or cannabinoids have also been assessed in experimental studies for their involvement in the biology of melanoma. Alpha-MSH and other neurohormones, as well as neuropeptides including substance P, CGRP, enkephalin, beta-endorphin, and even cellular and molecular agents (mast cells and nitric oxide, respectively), have all been implicated as potential factors in the development, growth, invasion, and dissemination of melanoma in a variety of in vitro and in vivo studies. In this review, we provide an overview of current evidence regarding the intricate effects of neuroendocrine factors in melanoma, including data reported in recent clinical trials, exploring the mechanisms involved, signaling pathways, and the recorded range of effects.

Current views on neuropeptides in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease involving skin barrier dysfunction and immune imbalance. However, the mechanism of AD is not clear completely and may be related to heredity and environment. Neuropeptides are a class of peptides secreted by nerve endings, they may play roles in promoting vasodilation, plasma extravasation, chemotaxis of inflammatory cells and mediating pruritus. Since itching and immune cell infiltration are the main manifestations of atopic dermatitis, to further investigate the impact of neuropeptides on AD, our review summarized the mechanisms of several common neuropeptides in AD and hypothesized that neuropeptides may be the novel potential targets in AD treatment.

Type I Interferon Production of Plasmacytoid Dendritic Cells under Control

One of the most powerful and multifaceted cytokines produced by immune cells are type I interferons (IFNs), the basal secretion of which contributes to the maintenance of immune homeostasis, while their activation-induced production is essential to effective immune responses. Although, each cell is capable of producing type I IFNs, plasmacytoid dendritic cells (pDCs) possess a unique ability to rapidly produce large amounts of them. Importantly, type I IFNs have a prominent role in the pathomechanism of various pDC-associated diseases. Deficiency in type I IFN production increases the risk of more severe viral infections and the development of certain allergic reactions, and supports tumor resistance; nevertheless, its overproduction promotes autoimmune reactions. Therefore, the tight regulation of type I IFN responses of pDCs is essential to maintain an adequate level of immune response without causing adverse effects. Here, our goal was to summarize those endogenous factors that can influence the type I IFN responses of pDCs, and thus might serve as possible therapeutic targets in pDC-associated diseases. Furthermore, we briefly discuss the current therapeutic approaches targeting the pDC-type I IFN axis in viral infections, cancer, autoimmunity, and allergy, together with their limitations defined by the Janus-faced nature of pDC-derived type I IFNs.

Pituitary adenylate cyclase-activating polypeptide/vasoactive intestinal peptide (Part 2): biology and clinical importance in central nervous system and inflammatory disorders

PURPOSE OF REVIEW

To discuss recent advances of vasoactive intestinal peptide/pituitary adenylate cyclase-activating polypeptide (VIP/PACAP) receptors in the selected central nervous system (CNS) and inflammatory disorders.

RECENT FINDINGS

Recent studies provide evidence that PACAP plays an important role in a number of CNS disorders, particularly the pathogenesis of headaches (migraine, etc.) as well as posttraumatic stress disorder and drug/alcohol/smoking addiction. VIP has important therapeutic effects in a number of autoimmune/inflammatory disorder such as rheumatoid arthritis. In some cases, these insights have advanced to therapeutic trials.

SUMMARY

Recent insights from studies of VIP/PACAP and their receptors in both CNS disorders (migraine, posttraumatic stress disorder, addiction [drugs, alcohol, smoking]) and inflammatory disorders [such as rheumatoid arthritis] are suggesting new treatment approaches. The elucidation of the importance of VIP/PACAP system in these disorders combined recent development of specific drugs acting on this system (i.e., monoclonal VIP/PACAP antibodies) will likely lead to importance novel treatment approaches in these diseases.

VIP modulates human macrophages phenotype via FPRL1 via activation of RhoA-GTPase and PLC pathways

OBJECTIVE AND DESIGN

This study is aimed at uncovering the signaling pathways activated by vasoactive intestinal peptide in human macrophages MATERIALS: Human peripheral blood mononuclear cell-derived macrophages were used for the in vitro investigation of the VIP-activated signaling pathways.

METHODS AND TREATMENT

Time-course and dose-response experiments and siRNA were used in human macrophages co-challenged with various concentrations of VIP and different MAPK pharmacologic inhibitors to investigate signaling pathways activated by VIP. Flow analysis was performed to assess the levels of CD11b, CD35 and CD66. Luminescence spectrometry was used to measure the levels of the released hydrogen peroxide and the intracellular calcium levels in the media.

RESULTS

Macrophages incubated with VIP showed increased phospho-AKT and phospho-ERK1/2 levels in a GTP-RhoA-GTPase-dependent manner. Similarly, VIP increased intracellular release of H₂O₂ and calcium via PLC and GTP-RhoA-GTPase, in addition to inducing the expression of CD11b, CD35, CD66 and MMP9. Furthermore, VIP activated P38 MAPK through the cAMP/PKA pathway but was independent of both PLC and RhoA signaling. The above-mentioned VIP effects were mediated via activation of the FPRL1 receptor.

CONCLUSION

VIP/FPRL1/VPAC/GTP-RhoA-GTPase signaling modulated macrophages phenotype through activation of multiple signaling pathways including ERK1/2, AKT, P38, ROS, cAMP and calcium.

The CNS and the Brain Tumor Microenvironment: Implications for Glioblastoma Immunotherapy

Glioblastoma (GBM) is the most common and aggressive malignant primary brain tumor in adults. Its aggressive nature is attributed partly to its deeply invasive margins, its molecular and cellular heterogeneity, and uniquely tolerant site of origin—the brain. The immunosuppressive central nervous system (CNS) and GBM microenvironments are significant obstacles to generating an effective and long-lasting anti-tumoral response, as evidenced by this tumor’s reduced rate of treatment response and high probability of recurrence. Immunotherapy has revolutionized patients’ outcomes across many cancers and may open new avenues for patients with GBM. There is now a range of immunotherapeutic strategies being tested in patients with GBM that target both the innate and adaptive immune compartment. These strategies include antibodies that re-educate tumor macrophages, vaccines that introduce tumor-specific dendritic cells, checkpoint molecule inhibition, engineered T cells, and proteins that help T cells engage directly with tumor cells. Despite this, there is still much ground to be gained in improving the response rates of the various immunotherapies currently being trialed. Through historical and contemporary studies, we examine the fundamentals of CNS immunity that shape how to approach immune modulation in GBM, including the now revamped concept of CNS privilege. We also discuss the preclinical models used to study GBM progression and immunity. Lastly, we discuss the immunotherapeutic strategies currently being studied to help overcome the hurdles of the blood–brain barrier and the immunosuppressive tumor microenvironment.

Function study of vasoactive intestinal peptide on chick embryonic bone development

Embryonic bone development is a complicated procedure and modulated by neuro-osteogenic interaction. Vasoactive intestinal peptide (VIP) was first identified as a neural vasodilator and further proved to possess multiple biological functions such as neurotransmitter and immune regulator. However, as a key peptide regulator presented in skeletal nerve fibers, the function of VIP on innervation and early bone development regulation has not fully been uncovered yet. In this study, the chick embryo has been used as an experimental model to address the effect of VIP on embryonic bone development. Our study results confirmed the innervation of peripheral nerve fibers into limb bone tissue, which was revealed by the detection of neurofilament (NF) and class III β-tubulin (TUJ-1) in bone tissue at various developing stages. The VIP mRNA and peptide expression level in bone tissue were also increased upon innervation progress. A chick embryonic chemical sympathectomy model was constructed by exposing chick embryos with neurotoxin 6-OHDA. The 6-OHDA exposure of the early chick embryo caused the reduction of neural crest formation and NF expression. 6-OHDA treatment also inhibited distal limb bone development as well as VIP expression. Furthermore, co-application of VIP with 6-OHDA exposure could rescue the inhibited osteogenesis activity and delayed bone development during embryogenesis. Taken together, these results reveal that VIP played an important role during innervation at early stage of bone development. VIP could restore chemical sympathectomy induced osteogenesis inhibition and bone development impair in chick embryos.

Panorama of mediators in postpancreatitis diabetes mellitus

PURPOSE OF REVIEW

To provide an overview of mediators involved in the pathogenesis of postacute pancreatitis diabetes mellitus.

RECENT FINDINGS

The 'holistic prevention of pancreatitis' framework has brought to the fore the sequelae of not only end-stage chronic pancreatitis and extensive pancreatic necrosis but also mild acute pancreatitis. Insights from the DORADO project have provided a wealth of information on the signalling molecules that do and do not affect glucose metabolism in individuals after mild acute pancreatitis and have challenged conventional views of the pathogenesis of postpancreatitis diabetes mellitus.

SUMMARY

Growing evidence compels a reconsideration of the dogma that mechanical β-cell destruction (and the resulting insulin deficiency) is the only underlying mechanism of postpancreatitis diabetes mellitus. Chronic low-grade inflammation, β-cell compensation, lipolysis, altered secretion of gut hormones, and changes in iron metabolism characterize postacute pancreatitis diabetes mellitus. Some of these are druggable targets that offer novel opportunities to reduce the burden of pancreatitis through tertiary prevention.

Exosomes carry IL-10 and antigen/MHC II complexes to induce antigen-specific oral tolerance

BACKGROUND

It is known that the immune tolerance can be naturally established in the intestine, while the mechanism by which the immune tolerance development in the intestine is not fully understood yet. Vasoactive intestinal peptides (VIP) has the immune regulatory functions. This study aims to investigate the role of VIP in the immune tolerance development in the intestine.

METHODS

Intestinal epithelial cell (IEC)-derived exosomes were prepared. The exosomes carried IL-10 and antigen/MHC II complexes. VIP-deficient (VIPd) mice and wild type mice were employed to test the role of VIP in the development of immune tolerance in the intestine.

RESULTS

VIPd mice failed to induce type 1 regulatory T cells (Tr1 cells) in the intestine and retarded the establishment of antigen (Ag)-specific immune tolerance. Exposure to VIP in the culture induced IL-10 expression in intestinal epithelial cells (IECs). Exosomes derived from ovalbumin (OVA, used as a specific Ag)/VIP-primed IECs carried IL-10 and OVA/MHC II complexes; these exosomes were designated IL10CARs (IL-10/chimeric antigen receptor-carrying exosomes). IL10CARs could recognize OVA-specific CD4⁺ T cells and converted OVA-specific CD4^± T cells to OVA-specific Tr1 cells. Administration of IL10CARs suppressed experimental food allergy.

CONCLUSIONS

The data show that IL10CARs are capable of suppressing experimental FA by inducing antigen-specific Tr1 cells, which has the translation potential for FA treatment.

Established and In-trial GPCR Families in Clinical Trials: A Review for Target Selection

The largest family of drug targets in clinical trials constitute of GPCRs (G-protein coupled receptors) which accounts for about 34% of FDA (Food and Drug Administration) approved drugs acting on 108 unique GPCRs. Factors such as readily identifiable conserved motif in structures, 127 orphan GPCRs despite various de-orphaning techniques, directed functional antibodies for validation as drug targets, etc. has widened their therapeutic windows. The availability of 44 crystal structures of unique receptors, unexplored non-olfactory GPCRs (encoded by 50% of the human genome) and 205 ligand receptor complexes now present a strong foundation for structure-based drug discovery and design. The growing impact of polypharmacology for complex diseases like schizophrenia, cancer etc. warrants the need for novel targets and considering the undiscriminating and selectivity of GPCRs, they can fulfill this purpose. Again, natural genetic variations within the human genome sometimes delude the therapeutic expectations of some drugs, resulting in medication response differences and ADRs (adverse drug reactions). Around ~30 billion US dollars are dumped annually for poor accounting of ADRs in the US alone. To curb such undesirable reactions, the knowledge of established and currently in clinical trials GPCRs families can offer huge understanding towards the drug designing prospects including "off-target" effects reducing economical resource and time. The druggability of GPCR protein families and critical roles played by them in complex diseases are explained. Class A, class B1, class C and class F are generally established family and GPCRs in phase I (19%), phase II(29%), phase III(52%) studies are also reviewed. From the phase I studies, frizzled receptors accounted for the highest in trial targets, neuropeptides in phase II and melanocortin in phase III studies. Also, the bioapplications for nanoparticles along with future prospects for both nanomedicine and GPCR drug industry are discussed. Further, the use of computational techniques and methods employed for different target validations are also reviewed along with their future potential for the GPCR based drug discovery.

Triggering receptor expressed on myeloid cells-1 (TREM-1) as a therapeutic target in infectious and noninfectious disease: a critical review

The triggering receptor expressed on myeloid cells-1 (TREM-1) is an innate immune receptor found in the surface of several immune and non-immune cells. Since its first description in 2000, this molecule and its soluble form (sTREM-1) have been implicated in many diseases with infectious and noninfectious origins. As an amplifier of inflammation, the membrane-associated TREM-1 (mTREM-1) isoform induces the production of pro-inflammatory mediators, thus contributing to the pathogenesis of diseases such as sepsis, arthritis, colitis and infections. In this context, many studies have used molecules capable of inhibiting TREM-1 activity as anti-inflammatory drugs. In this regard, a few peptides have been showing promising results in the amelioration of detrimental immune responses. Some commercially available drugs, including corticosteroids and antibiotics, with known anti-inflammatory effects, have also shown activity in TREM-1 signaling. Therefore, considering the potential of this receptor as a therapeutic target, the present review encompasses the main compounds explored so far in TREM-1 modulation, highlighting and critically discussing its effects and major drawbacks of such approaches.

Co-hybridized composite nanovesicles for enhanced transdermal eugenol and cinnamaldehyde delivery and their potential efficacy in ulcerative colitis

Percutaneous absorption of drugs can be enhanced by ethosomes, which are nanocarriers with excellent deformability and drug-loading properties. However, the ethanol within ethosomes increases phospholipid membrane fluidity and permeability, leading to drug leakage during storage. Here, we developed and characterized a new phospholipid nanovesicles that is co-hybridized with hyaluronic acid (HA), ethanol and the encapsulated volatile oil medicines (eugenol and cinnamaldehyde [EUG/CAH]) for transdermal administration. In comparison with EUG/CAH-loaded ethosomes (ES), the formulation stability and percutaneous drug absorption of EUG/CAH-loaded HA-immobilized ethosomes (HA-ES) were significantly improved. After transdermal administration of HA-ES, the interstitial cells of Cajal in the colon of rats with trinitrobenzene sulfonate-induced ulcerative colitis (UC) were significantly increased, and the stem cell factor/c-kit signaling pathway was partly repaired. Overall, HA-ES possesses excellent deformability and showed improved efficacy against UC compared with ES, which is demonstrated as a promising transdermal delivery vehicle for volatile oil medicines.

The role of glia in Parkinson's disease: Emerging concepts and therapeutic applications

Originally believed to primarily affect neurons, Parkinson's disease (PD) has recently been recognized to also affect the functions and integrity of microglia and astroglia, two cell categories of fundamental importance to brain tissue homeostasis, defense, and repair. Both a loss of glial supportive-defensive functions and a toxic gain of glial functions are implicated in the neurodegenerative process. Moreover, the chronic treatment with L-DOPA may cause maladaptive glial plasticity favoring a development of therapy complications. This chapter focuses on the pathophysiology of PD from a glial point of view, presenting this rapidly growing field from the first discoveries made to the most recent developments. We report and compare histopathological and molecular findings from experimental models of PD and human studies. We moreover discuss the important role played by astrocytes in compensatory adaptations taking place during presymptomatic disease stages. We finally describe examples of potential therapeutic applications stemming from an increased understanding of the important roles of glia in PD.