Mapping the CRF-urocortins system in human osteoarthritic and rheumatoid synovial fibroblasts: effect of vasoactive intestinal peptide

The role of nerve fibers and their neurotransmitters in regulating intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) has been the major contributor to chronic lower back pain (LBP). Abnormal apoptosis, senescence, and pyroptosis of IVD cells, extracellular matrix (ECM) degradation, and infiltration of immune cells are the major molecular alternations during IVDD. Changes at tissue level frequently occur at advanced IVD tissue. Ectopic ingrowth of nerves within inner annulus fibrosus (AF) and nucleus pulposus (NP) tissue has been considered as the primary cause for LBP. Innervation at IVD tissue mainly included sensory and sympathetic nerves, and many markers for these two types of nerves have been detected since 1940. In fact, in osteoarthritis (OA), beyond pain transmission, the direct regulation of neuropeptides on functions of chondrocytes have attracted researchers' great attention recently. Many physical and pathological similarities between joint and IVD have shed us the light on the neurogenic mechanism involved in IVDD. Here, an overview of the advances in the nervous system within IVD tissue will be performed, with a discussion on in the role of nerve fibers and their neurotransmitters in regulating IVDD. We hope this review can attract more research interest to address neuromodulation and IVDD itself, which will enhance our understanding of the contribution of neuromodulation to the structural changes within IVD tissue and inflammatory responses and will help identify novel therapeutic targets and enable the effective treatment of IVDD disease.

A Clinical Approach for the Use of VIP Axis in Inflammatory and Autoimmune Diseases

The neuroendocrine and immune systems are coordinated to maintain the homeostasis of the organism, generating bidirectional communication through shared mediators and receptors. Vasoactive intestinal peptide (VIP) is the paradigm of an endogenous neuropeptide produced by neurons and endocrine and immune cells, involved in the control of both innate and adaptive immune responses. Exogenous administration of VIP exerts therapeutic effects in models of autoimmune/inflammatory diseases mediated by G-protein-coupled receptors (VPAC1 and VPAC2). Currently, there are no curative therapies for inflammatory and autoimmune diseases, and patients present complex diagnostic, therapeutic, and prognostic problems in daily clinical practice due to their heterogeneous nature. This review focuses on the biology of VIP and VIP receptor signaling, as well as its protective effects as an immunomodulatory factor. Recent progress in improving the stability, selectivity, and effectiveness of VIP/receptors analogues and new routes of administration are highlighted, as well as important advances in their use as biomarkers, contributing to their potential application in precision medicine. On the 50th anniversary of VIP's discovery, this review presents a spectrum of potential clinical benefits applied to inflammatory and autoimmune diseases.

Role of vasoactive intestinal peptide in osteoarthritis

Vasoactive intestinal peptide (VIP) plays important roles in many biological functions, such as, stimulation of contractility in the heart, vasodilation, promoting neuroendocrine-immune communication, lowering arterial blood pressure, and anti-inflammatory and immune-modulatory activity. Osteoarthritis (OA) is a chronic and degenerative bone disease, which is one of the most common causes of disability and most common in both sexes as people become older. Interestingly VIP can prevent chronic cartilage damage and joint remodeling. This review article provides update information on the association of VIP and OA and its treatment. Evidences suggest that VIP is down-regulated in synovial fluid of OA, and VIP down-regulation leads to increase in the production of pro-inflammatory cytokines that might contribute to the pathogenesis of OA; however contradictory reports also exist suggesting that accumulation of VIP in joints can also contribute OA. A number of studies indicated that up-regulation of VIP can counteract the action of pro-inflammatory stimuli and alleviate the pain in OA. More clinical investigations are necessary to determine the biology of VIP and its therapeutic potential in OA that might represent the future standards of care for OA.

VIP and CRF reduce ADAMTS expression and function in osteoarthritis synovial fibroblasts

ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family is known to play an important role in the pathogenesis of osteoarthritis (OA), working on aggrecan degradation or altering the integrity of extracellular matrix (ECM). Thus, the main purpose of our study was to define the role of vasoactive intestinal peptide (VIP) and corticotrophin-releasing factor (CRF), as immunoregulatory neuropeptides, on ADAMTS production in synovial fibroblasts (SF) from OA patients and healthy donors (HD). OA- and HD-SF were stimulated with pro-inflammatory mediators and treated with VIP or CRF. Both neuropeptides decreased ADAMTS-4, -5, -7 and -12 expressions, aggrecanase activity, glycosaminoglycans (GAG), and cartilage oligomeric matrix protein (COMP) degradation after stimulation with fibronectin fragments (Fn-fs) in OA-SF. After stimulation with interleukin-1β, VIP reduced ADAMTS-4 and -5, and both neuropeptides decreased ADAMTS-7 production and COMP degradation. Moreover, VIP and CRF reduced Runx2 and β-catenin activation in OA-SF. Our data suggest that the role of VIP and CRF on ADAMTS expression and cartilage degradation could be related to the OA pathology since scarce effects were produced in HD-SF. In addition, their effects might be greater when a degradation loop has been established, given that they were higher after stimulation with Fn-fs. Our results point to novel OA therapies based on the use of neuropeptides, since VIP and CRF are able to stop the first critical step, the loss of cartilage aggrecan and the ECM destabilization during joint degradation.

Biomarkers predicting a need for intensive treatment in patients with early arthritis

The heterogeneous nature of rheumatoid arthritis (RA) complicates early recognition and treatment. In recent years, a growing body of evidence has demonstrated that intervention during the window of opportunity can improve the response to treatment and slow—or even stop—irreversible structural changes. Advances in therapy, such as biologic agents, and changing approaches to the disease, such as the treat to target and tight control strategies, have led to better outcomes resulting from personalized treatment to patients with different prognostic markers. The various biomarkers identified either facilitate early diagnosis or make it possible to adjust management to disease activity or poor outcomes. However, no single biomarker can bridge the gap between disease onset and prescription of the first DMARD, and traditional biomarkers do not identify all patients requiring early aggressive treatment. Furthermore, the outcomes of early arthritis cohorts are largely biased by the treatment prescribed to patients; therefore, new challenges arise in the search for prognostic biomarkers. Herein, we discuss the value of traditional and new biomarkers and suggest the need for intensive treatment as a new surrogate marker of poor prognosis that can guide therapeutic decisions in the early stages of RA.

Neuropeptide receptors as potential drug targets in the treatment of inflammatory conditions

Cross-talk between the nervous, endocrine and immune systems exists via regulator molecules, such as neuropeptides, hormones and cytokines. A number of neuropeptides have been implicated in the genesis of inflammation, such as tachykinins and calcitonin gene-related peptide. Development of their receptor antagonists could be a promising approach to anti-inflammatory pharmacotherapy. Anti-inflammatory neuropeptides, such as vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide, α-melanocyte-stimulating hormone, urocortin, adrenomedullin, somatostatin, cortistatin, ghrelin, galanin and opioid peptides, are also released and act on their own receptors on the neurons as well as on different inflammatory and immune cells. The aim of the present review is to summarize the most prominent data of preclinical animal studies concerning the main pharmacological effects of ligands acting on the neuropeptide receptors. Promising therapeutic impacts of these compounds as potential candidates for the development of novel types of anti-inflammatory drugs are also discussed.

Increased alcohol consumption in urocortin 3 knockout mice is unaffected by chronic inflammatory pain

AIMS

Stress neurocircuitry may modulate the relationship between alcohol drinking and chronic pain. The corticotropin-releasing factor (CRF) system is crucial for regulation of stress responses. The current study aimed to elucidate the role of the endogenous CRF ligand Urocortin 3 (Ucn3) in the relationship between alcohol drinking behavior and chronic pain using a genetic approach.

METHODS

Ucn3 (KO) and wildtype (WT) littermates were subjected to a 24-h access drinking procedure prior to and following induction of chronic inflammatory pain.

RESULTS

Ucn3 KO mice displayed significantly increased ethanol intake and preference compared with WT across the time course. There were no long-term effects of chronic pain on alcohol drinking behavior, regardless of genotype, nor any evidence for alcohol-induced analgesia.

CONCLUSION

The increased drinking in Ucn3 KO supports a role for this peptide in alcohol-related behavior. These data suggest the necessity for more research exploring the relationship between alcohol drinking, chronic pain and the CRF system in rodent models.

Serum levels of vasoactive intestinal peptide as a prognostic marker in early arthritis

Objective

Suitable biomarkers are essential for the design of therapeutic strategies in personalized medicine. Vasoactive intestinal peptide (VIP) has demonstrated immunomodulatory properties in autoimmune murine and ex vivo human models. Our aim was to study serum levels of VIP during the follow-up of an early arthritis (EA) cohort and to analyze its value as a biomarker predicting severity and therapeutic requirements.

Methods

Data from 91 patients on an EA register were analyzed (76% rheumatoid arthritis (RA), 24% undifferentiated arthritis, 73% women, and median age 54 years; median disease duration at entry, 5.4 months). We collected per protocol sociodemographic, clinical, and therapeutic data. VIP levels were determined by enzyme immunoassay in sera harvested from the 91 patients (353 visits; 3.9 visit/patient) and from 100 healthy controls. VIP values below the 25^th percentile of those assessed in healthy population were considered low. To determine the effect of independent variables on VIP levels, we performed a longitudinal multivariate analysis nested by patient and visit. A multivariate ordered logistic regression was modeled to determine the effect of low VIP serum levels on disease activity at the end of follow-up.

Results

VIP concentrations varied considerably across EA patients. Those fulfilling the criteria for RA had the lowest values in the whole sample, although no significant differences were observed compared with healthy donors. Disease activity, which was assessed using DAS28, inversely correlated with VIP levels. After a two-year follow-up, those patients with low baseline levels of VIP displayed higher disease activity and received more intensive treatment.

Conclusion

Patients who are unable to up-regulate VIP seem to have a worse clinical course despite receiving more intense treatment. Therefore, measurement of VIP levels may be suitable as a prognostic biomarker.

Urokinase plasminogen activator system in synovial fibroblasts from osteoarthritis patients: modulation by inflammatory mediators and neuropeptides

Plasminogen activators are specific proteolytic enzymes implicated in a variety of basic biological processes. The expression of the urokinase plasminogen activator system components is increased in some human diseases, including osteoarthritis. We sought to study the effect of two components of the inflamed synovial microenvironment on this system, IL-1β and fibronectin fragments, elucidating whether corticotropin-releasing factor (CRF) and vasoactive intestinal peptide (VIP) neuropeptides modulate it, and analyzing the physiological consequences in joint destruction by measuring matrix metalloproteinases-9 and metalloproteinases-13 levels in osteoarthritis fibroblast-like synoviocytes. We showed that IL-1β and fibronectin fragments stimulated urokinase system contributing to the perpetuation of the destructive cascade in joint. VIP modulated, even at constitutive level, this system, also counteracting the effect of both inflammatory stimuli. However, CRF seemed to be ineffective in controlling the production of these proteinases. Moreover, VIP was able to reduce the constitutive expression of matrix metalloproteinase-13 and the levels of both matrix metalloproteinases after stimulation with the pro-inflammatory stimuli. Our results suggest that the presence of early and later inflammatory mediators, such as IL-1β and fibronectin fragments, increases the urokinase system and the matrix metalloproteinases levels. Whereas CRF did not affect this system, VIP counteracts these actions supporting its therapeutic potential for the treatment of osteoarthritis.

Identification of transcription regulatory relationships in rheumatoid arthritis and osteoarthritis

Rheumatoid arthritis (RA) is recognized as the most crippling or disabling type of arthritis, and osteoarthritis (OA) is the most common form of arthritis. These diseases severely reduce the quality of life, and cause high socioeconomic burdens. However, the molecular mechanisms of RA and OA development remain elusive despite intensive research efforts. In this study, we aimed to identify the potential transcription regulatory relationships between transcription factors (TFs) and differentially co-expressed genes (DCGs) in RA and OA, respectively. We downloaded the gene expression profiles of RA and OA from the Gene Expression Omnibus and analyzed the gene expression using computational methods. We identified a set of 4,076 DCGs in pairwise comparisons between RA and OA patients, RA and normal donors (NDs), or OA and ND. After regulatory network construction and regulatory impact factor analysis, we found that EGR1, NFE2L1, and NFYA were crucial TFs in the regulatory network of RA and NFYA, CBFB, CREB1, YY1 and PATZ1 were crucial TFs in the regulatory network of OA. These TFs could regulate the DCGs expression to involve RA and OA by promoting or inhibiting their expression. Altogether, our work may extend our understanding of disease mechanisms and may lead to an improved diagnosis. However, further experiments are still needed to confirm these observations.

Expression of synovial fluid and articular cartilage VIP in human osteoarthritic knee: a new indicator of disease severity?

OBJECTIVES

Vasoactive intestinal peptide (VIP) is a molecule shared by the neuroendocrine immune network and is considered to be a potential candidate for treatment of inflammatory and autoimmune diseases. Although some recent studies demonstrate that VIP has a protective role in animal RA models, its variant in different disease grade of OA remains uncertain.

DESIGN AND METHODS

Fifty patients with primary knee OA and ten controls with severe trauma were enrolled. Synovial fluid and articular cartilage samples were collected from specimens of total knee arthroplasty (TKA) or knee above amputation. VIP levels in these samples were assessed by ELISA and immunohistochemistry. Kellgren-Lawrence criteria and Mankin score were taken to determine the disease severity.

RESULTS

Compared to the controls, OA patients have lower VIP concentration in synovial fluid (659.70±112.79, 95%CI 579.01-740.38 vs 470.83±156.40, 95%CI 426.38-515.28 pg/mL, P<0.001) and articular cartilage (0.26±0.02, 95%CI 0.24-0.28 vs 0.20±0.04, 95%CI 0.18-0.21, P<0.001). Subsequent analysis show that the VIP expression in synovial fluid is markedly correlated with its OD in articular cartilage (Pearson's r=0.580, P<0.001). Furthermore, the synovial fluid and articular cartilage levels of VIP both demonstrated to be negatively correlated with severity of disease (Spearman's ρ=0.838, P<0.001; Spearman's ρ=0.814, P<0.001).

CONCLUSIONS

VIP in synovial fluid and articular cartilage is negatively associated with progressive joint damage in OA and is a potential indictor of disease severity.