Vasoactive intestinal peptide is required in the maintenance of immune regulatory competency of immune regulatory monocytes

Vasoactive intestinal peptide alleviates food allergy via restoring regulatory B cell functions

The immune regulatory cell dysfunction is associated with many immune diseases including food allergy (FA). This study aims to investigate the role of vasoactive intestinal peptide (VIP) in the maintenance of regulatory B cell (Br cell)'s immune suppressive functions by stabilizing thrombospondin (TSP1) expression. In this study, blood samples were collected from patients with food allergy (FA) and healthy control (HC) subjects. Br cells were isolated from the samples through flow cytometry cell sorting and analyzed by immunological approaches to determine the immune regulatory capacity. We found that the immune suppressive functions of Br cells were impaired in FA patients. The serum VIP levels were associated with the production of immune suppressive function-related mediators (interleukin-10, IL-10) of Br cells in FA patients. VIP counteracted IL-10 mRNA decay in Br cells by up regulating the TSP1 expression. TSP1 inhibited tristetraprolin (TTP) to prevent IL-10 mRNA decay in Br cells. Administration of VIP inhibited FA response through restoration of immune suppressive functions in Br cells. In conclusion, administration of VIP can alleviate FA response through up regulating expression of TSP1 to stabilize IL-10 expression in FA Br cells and recover the immune regulatory functions. The results have translational potential for the treatment of FA and other disorders associated with immune regulatory dysfunction of Br cells.

An Overview of VPAC Receptors in Rheumatoid Arthritis: Biological Role and Clinical Significance

The axis comprised by the Vasoactive Intestinal Peptide (VIP) and its G protein-coupled receptors (GPCRs), VPAC1, and VPAC2, belong to the B1 family and signal through Gs or Gq proteins. VPAC receptors seem to preferentially interact with Gs in inflammatory cells, rather than Gq, thereby stimulating adenylate cyclase activity. cAMP is able to trigger various downstream pathways, mainly the canonical PKA pathway and the non-canonical cAMP-activated guanine nucleotide exchange factor (EPAC) pathway. Classically, the presence of VPACs has been confined to the plasma membrane; however, VPAC1 location has been described in the nuclear membrane in several cell types such as activated Th cells, where they are also functional. VPAC receptor signaling modulates a number of biological processes by tipping the balance of inflammatory mediators in macrophages and other innate immune cells, modifying the expression of TLRs, and inhibiting MMPs and the expression of adhesion molecules. Receptor signaling also downregulates coagulation factors and acute-phase proteins, promotes Th2 over Th1, stimulates Treg abundance, and finally inhibits a pathogenic Th17 profile. Thus, the VIP axis signaling regulates both the innate and adaptive immune responses in several inflammatory/autoimmune diseases. Rheumatoid arthritis (RA) is a complex autoimmune disease that develops on a substrate of genetically susceptible individuals and under the influence of environmental factors, as well as epigenetic mechanisms. It is a heterogeneous disease with different pathogenic mechanisms and variable clinical forms between patients with the same diagnosis. The knowledge of VIP signaling generated in both animal models and human ex vivo studies can potentially be translated to clinical reality. Most recently, the beneficial effects of nanoparticles of VIP self-associated with sterically stabilized micelles have been reported in a murine model of RA. Another novel research area is beginning to define the receptors as biomarkers in RA, with their expression levels shown to be associated with the activity of the disease and patients-reported impairment. Therefore, VPAC expression together VIP genetic variants could allow patients to be stratified at the beginning of the disease with the purpose of guiding personalized treatment decisions.