A role for calcitonin gene related peptide (CGRP) in the regulation of early B lymphocyte differentiation

Altered immunity in migraine: a comprehensive scoping review

BACKGROUND

The pathogenesis of migraine remains unclear; however, a large body of evidence supports the hypothesis that immunological mechanisms play a key role. Therefore, we aimed to review current studies on altered immunity in individuals with migraine during and outside attacks.

METHODS

We searched the PubMed database to investigate immunological changes in patients with migraine. We then added other relevant articles on altered immunity in migraine to our search.

RESULTS

Database screening identified 1,102 articles, of which 41 were selected. We added another 104 relevant articles. We found studies reporting elevated interictal levels of some proinflammatory cytokines, including IL-6 and TNF-α. Anti-inflammatory cytokines showed various findings, such as increased TGF-β and decreased IL-10. Other changes in humoral immunity included increased levels of chemokines, adhesion molecules, and matrix metalloproteinases; activation of the complement system; and increased IgM and IgA. Changes in cellular immunity included an increase in T helper cells, decreased cytotoxic T cells, decreased regulatory T cells, and an increase in a subset of natural killer cells. A significant comorbidity of autoimmune and allergic diseases with migraine was observed.

CONCLUSIONS

Our review summarizes the findings regarding altered humoral and cellular immunological findings in human migraine. We highlight the possible involvement of immunological mechanisms in the pathogenesis of migraine. However, further studies are needed to expand our knowledge of the exact role of immunological mechanisms in migraine pathogenesis.

Calcitonin gene-related peptide is a key neurotransmitter in the neuro-immune axis

The question of how the neural and immune systems interact in host defense is important, integrating a system that senses the whole body with one that protects. Understanding the mechanisms and routes of control could produce novel and powerful ways of promoting and enhancing normal functions as well as preventing or treating abnormal functions. Fragmentation of biological research into specialities has resulted in some failures in recognizing and understanding interactions across different systems and this is most striking across immunology, hematology, and neuroscience. This reductionist approach does not allow understanding of the in vivo orchestrated response generated through integration of all systems. However, many factors make the understanding of multisystem cross-talk in response to a threat difficult, for instance the nervous and immune systems share communication molecules and receptors for a wide range of physiological signals. But, it is clear that physical, hard-wired connections exist between the two systems, with the key link involving sensory, unmyelinated nerve fibers (c fibers) containing the neuropeptide calcitonin gene-related peptide (CGRP), and modified macrophages, mast cells and other immune and host defense cells in various locations throughout the body. In this review we will therefore focus on the induction of CGRP and its key role in the neuroimmune axis.

Effects of calcitonin gene-related peptide on the immune privilege of human hair follicles

The hair follicle is a widely available and instructive miniature organ in the human body that experiences major histocompatibility complex (MHC) class I dependent immune privilege (IP). There are various regulation factors that act on the generation, maintenance, and collapse of hair follicle IP. Neuropeptides such as calcitonin gene-related peptide (CGRP) are created in many organs, including skin, and display various immune regulation effects. The purpose of this study was to investigate the phenotypic effect of CGRP on the hair follicle's IP. First, we used interferon-γ (IFN-γ) to generate ectopic MHC antigen expression model in cultured human hair follicles as previously described. Then, we examined the effects of CGRP on the regulation of ectopic MHC antigen expression in cultured human hair follicles using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemical staining techniques. IFN-γ (75 IU/ml) induced ectopic MHC expression. CGRP down-regulated INF-γ-induced ectopic MHC class I mRNA expression. These down-regulated effects were especially evident in 10(-8)M. In addition, CGRP also suppressed the staining intensity related to the expression of MHC class I and MHC class I-pathway related molecules (β2-microglobulin), but had no effect on MHC class II antigen expression. Taken together, these results indicate that CGRP might be an important regulatory factor for IP maintenance and restoration of IP via suppression of MHC class I antigen.

Functional expression of the calcitonin receptor by human T and B cells

The calcitonin receptor (CTR) is a seven-transmembrane-domain G-protein-coupled receptor that regulates calcium metabolism and bone resorption by osteoclasts. Here we demonstrate that high levels are expressed by normal human T and B lymphocytes from tonsils and peripheral blood in relation to their activation status, as CTR(+) T cells are prone to produce IFN-gamma after TCR stimulation. The receptor is also highly expressed on B cells from chronic lymphocytic leukemia patients, thus suggesting a correlation between its expression, their proliferative extent as well as their memory, antigen-experienced phenotype. Moreover, we found that binding of the receptor with salmon calcitonin induces an increase of intracellular calcium(2+) in peripheral lymphocytes. This effect is involved in several lymphocyte immune functions, as cytosolic calcium(2+) levels regulate both cell proliferation and cytokine production. In our hands, the increase of calcium(2+) levels by CTR binding with sCT induced a dose-dependent cell proliferation. We therefore suppose that expression of this functional receptor may contribute to the modulation of cytoplasmic calcium(2+) levels needed to regulate T and B cell activation and perhaps other immune functions.

Expression and function of the calcitonin receptor by myeloma cells in their osteoclast-like activity in vitro

Malignant plasma cells exert osteoclast-like activity in vitro. We investigated the function of the calcitonin (CT) receptor (R) on myeloma cells from patients and in myeloma cell lines. Primary myeloma cells expressed high CTR levels whereas the cell lines uniformly exposed the CTR-2 variant expressed by osteoclasts. Treatment of myeloma cell lines with CT modified the intracellular Ca(2+) and cAMP levels, suggesting the activation of both PKC and PKA pathways, and abrogated their bone resorptive property as erosive pits on osteologic substrates. Thus, the expression, sensitivity and function of CTR-2 in myeloma cells emphasize their osteoclast-like behavior in vitro.

Mobilisation of specific T cells from lymph nodes in contact sensitivity requires substance P

Capsaicin-mediated depletion of neuropeptides in the skin was previously shown to abolish a dinitrocholorobenzene (DNCB)-induced contact sensitivity (CS) response. To understand the basis for this disruption, we explored whether nerve fibres innervating the draining lymph node (LN) could be involved. As expected, removal of the draining LN after DNCB sensitisation abolished the CS response. Furthermore, the CS response could be abolished by destroying the nerve fibres in the draining LN and could be restored by providing the LN with the neuropeptide substance P. The size of the CS response restored by substance P was dose dependent. The response was also inhibited by exposing the lymph node to a neurokinin-1 receptor antagonist which blocks binding of substance P. The results suggest that an afferent signal from the skin via the sympathetic arm of the central nervous system evokes an efferent signal to the LN which combines to regulate the CS response. The efferent signal may serve to control or release from the LN primed effector lymphocytes into the circulation.

Molecular cloning and characterization of mouse calcitonin gene-related peptide receptor

The calcitonin gene-related peptide (CGRP) plays important roles as a neurotransmitter/neuromodulator in the central nervous system, and as a potent vasodilator when secreted from peripheral, perivascular nerves through its specific receptors. In this study, we cloned mouse cDNA counterparts of the human CGRP receptor composed of calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein 1 (RAMP1) and examined the signal transduction mechanism through the CGRP receptor. Mouse CRLR (mCRLR) is a 462-amino acid G protein-coupled heptahelical receptor, and mouse RAMP1 (mRAMP1) is a 148-amino acid single membrane-spanning protein with a short cytoplasmic portion. Specific binding of (125)I-CGRP was detected only when both mCRLR and mRAMP1 cDNAs were cotransfected to COS-7 cells, and the Kd value of the receptor was 2.2 x 10(-10) M. CGRP induced a marked elevation of the intracellular cAMP levels in COS-7 cells cotransfected with mCRLR and mRAMP1. CGRP signaling through the mCRLR/mRAMP1 receptor complex was found to increase the promoter activities of cyclic AMP responsive element and serum responsive element in the co-transfected HeLa cells. These results indicate that mCRLR and mRAMP1 constitute a functional mouse CGRP receptor for the transduction of CGRP signaling by PKA and extracellular signal-regulated kinase signal transduction pathways.

NGF modulates CGRP synthesis in human B-lymphocytes: a possible anti-inflammatory action of NGF?

We investigated whether the sensory neuropeptide, calcitonin gene-related peptide (CGRP), could be synthesised by human lymphocytes. Our results indicate that in activated B-cells, there is a strong expression of CGRP gene transcripts, which is almost absent in resting cells. Since B-cells autocrinally produce NGF, the neutralisation of endogenous NGF by anti-NGF antibodies resulted in a marked reduction in CGRP expression in both resting and activated B-cells. Thus, NGF appears to directly affect the synthesis of CGRP in B-cells as in sensory neurons. By regulating CGRP synthesis in lymphocytes and neuronal cells, NGF can influence the intensity and duration of the immune response.

Distinct gene expression profiling in chronic lymphocytic leukemia with 11q23 deletion

Chronic lymphocytic leukemia (CLL) is a heterogeneous disease with regard to its clinical course. The limitations of the methods currently available for prognostic assessment in CLL do not allow accurate prediction of the risk of disease progression in individual patients. The recently developed cDNA array technique provides a unique opportunity to study gene expression in various malignancies. To identify new molecular markers for prognostication of CLL patients, we analyzed cDNA arrays by using hierarchical clustering and standard statistic t-test on 34 CLL patients. We found significant expression differences in 78 genes compared to the reference tonsillar B lymphocytes. A cluster of genes, LCP1, PARP, BLR1, DEK, NPM, MCL1, SLP76, STAM, HIVEP1, EVI2B, CD25, HTLF, HIVEP2, BCL2, MNDA, PBX3, EB12, TCF1, CGRP, CD14, ILB, GZMK, GPR17 and CD79B, was associated (P < 0.05) with the unfavorable 11q deletion and also with the unfavorable Binet stages B and C. We present here gene expression profiling that is associated with CLL patients with the 11q23 deletion. Many of the genes in the cluster have not previously been shown to be related to the initiation or progression of CLL. These novel findings provide fundamental information for further attempts to understand the interaction of the clustered genes in the leukomogenesis of CLL in order to better design treatments aimed at specific molecular target(s).

Inhibition of NF-kappaB activity and enhancement of apoptosis by the neuropeptide calcitonin gene-related peptide

Calcitonin gene-related peptide (CGRP) is a neuropeptide produced by the central and peripheral nervous systems and by endocrine cells. CGRP exerts diverse biological effects on the cardiovascular, gastrointestinal, respiratory, central nervous and immune systems. Little is known, however, about the molecular mechanisms that mediate CGRP effects. Using the NFkappaB-luciferase reporter transgenic mice, here we show that CGRP selectively inhibits NF-kappaB-mediated transcription in thymocytes in vitro and in vivo. In contrast, CGRP does not affect transcription mediated by the AP-1 and NFAT transcription factors. CGRP inhibits the accumulation of NF-kappaB complexes in the nucleus by preventing phosphorylation and degradation of the NF-kappaB inhibitor IkappaB. Inhibition of NF-kappaB activity is associated with the induction of apoptosis by CGRP in thymocytes. Together these results demonstrate for the first time the selective implication of the NF-kappaB signaling pathway in the regulatory function of the neuropeptide CGRP. Our study suggests a potential molecular mechanism by which CGRP can induce cell death in thymocytes.

Elevated circulating calcitonin gene-related peptide in umbilical cord and infant blood associated with maternal and neonatal sepsis and shock

The role of the sensory neuropeptide calcitonin gene-related peptide (CGRP) was studied in preterm and term neonates with sepsis and shock. CGRP levels in blood were measured by RIA. The identity of immunoreactive CGRP (irCGRP) in adult and infant human blood was confirmed by reverse phase-HPLC. CGRP levels were analyzed in a total of 189 samples (95 from cord blood and 94 from neonates). The gestational ages ranged from 24 to 43 wk, and the birth weights ranged from 520 to 4445 g. Cord samples were collected immediately after delivery and infant blood samples were collected within 12 h of birth. Samples were coded, and the data were assigned to groups after determination of CGRP levels. There was a weight- and gestation-dependent increase in irCGRP in the newborn population. The direct correlation of circulating CGRP with ascending birth weight and gestation may have significance in the development of the fetus. Infants with and without certain complications were grouped in 500-g intervals. CGRP levels in cord blood were significantly elevated when certain stressful situations existed in the mother. These included culture-positive chorioamnionitis, placental abruption, and severe preeclampsia. There was a similar elevation in CGRP in patient blood in infants with culture-positive sepsis and/or shock with blood pressure <2 SD from the mean for corresponding gestation. CGRP levels did not differ between male and female infants and did not appear to be influenced by type of delivery (vaginal versus cesarean section). There was no significant difference in CGRP level between cord and patient blood in preterm neonates, but at term gestation cord blood levels were slightly higher than those in the patient blood. These results suggest that inflammation and hemodynamic imbalance (e.g. shock) are associated with increased in CGRP levels in the circulation in neonates. Future studies will focus on the biologic effects of elevated CGRP during neonatal complications and will examine the utility of CGRP measurement for diagnosis and treatment of disease in preterm infants.