Calcitonin Gene-related Peptide Secretion Research Articles

Calcitonin gene‑related peptide alleviates hyperoxia‑induced human alveolar cell injury via the CGRPR/TRPV1/Ca2+ axis.

Although exogenous calcitonin gene‑related peptide (CGRP) protects against hyperoxia‑induced lung injury (HILI), the underlying mechanisms remain unclear. The present study attempted to elucidate the molecular mechanism by which CGRP protects against hyperoxia‑induced alveolar cell injury. Human alveolar A549 cells were treated with 95% hyperoxia to establish a hyperoxic cell injury model. ELISA was performed to detect the CGRP secretion. Immunofluorescence, quantitative (q)PCR, and western blotting were used to detect the expression and localization of CGRP receptor (CGRPR) and transient receptor potential vanilloid 1 (TRPV1). Cell counting kit‑8 and flow cytometry were used to examine the proliferation and apoptosis of treated cells. Digital calcium imaging and patch clamp were used to analyze the changes in intracellular Ca2+ signaling and membrane currents induced by CGRP in A549 cells. The mRNA and protein expression levels of Cyclin D1, proliferating cell nuclear antigen (PCNA), Bcl‑2 and Bax were detected by qPCR and western blotting. The expression levels of CGRPR and TRPV1 in A549 cells were significantly downregulated by hyperoxic treatment, but there was no significant difference in CGRP release between cells cultured under normal air and hyperoxic conditions. CGRP promoted cell proliferation and inhibited apoptosis in hyperoxia, but selective inhibitors of CGRPR and TRPV1 channels could effectively attenuate these effects; TRPV1 knockdown also attenuated this effect. CGRP induced Ca2+ entry via the TRPV1 channels and enhanced the membrane non‑selective currents through TRPV1 channels. The CGRP‑induced increase in intracellular Ca2+ was reduced by inhibiting the phospholipase C (PLC)/protein kinase C (PKC) pathway. Moreover, PLC and PKC inhibitors attenuated the effects of CGRP in promoting cell proliferation and inhibiting apoptosis. In conclusion, exogenous CGRP acted by inversely regulating the function of TRPV1 channels in alveolar cells. Importantly, CGRP protected alveolar cells from hyperoxia‑induced injury via the CGRPR/TRPV1/Ca2+ axis, which may be a potential target for the prevention and treatment of the HILI.

Propionate alleviates itch in murine models of atopic dermatitis by modulating sensory TRP channels of dorsal root ganglion.

Itch is the most common symptom of atopic dermatitis (AD) and significantly decreases the quality of life. Skin microbiome is involved in AD pathogenesis, whereas its role in the regulation of itch remains elusive. In this study, we aimed to investigate the effects of skin microbial metabolite propionate on acute and chronic pruritus and to explore the mechanism. Using various mouse models of itch, the roles of propionate were explored by behavioral tests and histopathology/immunofluorescent analysis. Primary-cultured dorsal root ganglion neurons and HEK293 cells expressing recombinant human TRP channels were utilized for invitro calcium imaging/in vivo miniature two-photon imaging in combination with electrophysiology and molecular docking approaches for investigation of the mechanism. Propionate significantly alleviated itch and alloknesis in various mouse models of pruritus and AD and decreased the density of intraepidermal nerve fibers. Propionate reduced the responsiveness of dorsal root ganglion neurons to pruritogens invitro, attenuated the hyper-excitability in sensory neurons in MC903-induced AD model, and inhibited capsaicin-evoked hTRPV1 currents (IC50 = 20.08 ± 1.11 μM) via interacting with the vanilloid binding site. Propionate also decreased the secretion of calcitonin gene-related peptide by nerves in MC903-induced AD mouse model, which further attenuated itch and skin inflammation. Our study revealed a protective effect of propionate against persistent itch through direct modulation of sensory TRP channels and neuropeptide production in neurons. Regulation of itch via the skin microbiome might be a novel strategy for the treatment of AD.

Rehmannia alcohol extract inhibits neuropeptide secretion and alleviates osteoarthritis pain through cartilage protection

Osteoarthritis (OA) is a common joint disease characterized by chronic pain, and the perception of pain is closely associated with brain function and neuropeptide regulation. Rehmannia is common plant herb with anti-inflammatory and analgesic properties that is used to treat OA. However, it is unclear whether Rehmannia alleviates OA-related pain via regulation of neuropeptides and brain function. We examined the pain relief regulatory pathway in OA after treatment with Rehmannia by verifying the therapeutic effect of Rehmannia alcohol extract in vivo and vitro and exploring of the potential mechanism underlying the analgesic effect of Rahmanian using functional magnetic resonance imaging and measuring neuropeptide secretion. Our results showed that Rehmannia alcohol extract and the related active ingredient, Rehmannioside D, can delay cartilage degradation and alleviate inflammation in OA rats. The Rehmannia alcohol extract can also relieve OA pain, reduce the secretion of calcitonin gene-related peptide (CGRP) and substance P (SP), and reverse the pathological changes in the cerebral cortex and hippocampus. Our research results demonstrate that Rehmannia alleviates OA pain by protecting cartilage, preventing the stimulation of inflammatory factors on neuropeptide secretion, and influencing the relevant functional areas of the brain.

Neuronal TRPV1-CGRP axis regulates bone defect repair through Hippo signaling pathway

Transient receptor potential vanilloid type 1 (TRPV1) is highly expressed on sensory neurons where it serves as a polymodal receptor for detecting physical and chemical stimuli. However, the role of TRPV1 in bone metabolism remains largely unclear. This study aimed to investigate the underlying mechanism of neuronal TRPV1 in regulating bone defect repair. In vivo experiment verified that TRPV1 activation could trigger dorsal root ganglion (DRG) producing the neuropeptide calcitonin gene-related peptide (CGRP) in mice. The accelerated bone healing of femoral defect in this process was observed compared to the control group (p < 0.05). Conversely, Trpv1 knockdown led to reduced CGRP expression in DRG and nerves innervating femur bone tissue, following impaired bone formation and osteogenic capability in the defect region (p < 0.05), which could be rescued by local CGRP treatment. In vitro, results revealed that TRPV1 function in DRG neurons contributed essentially to the regulation of osteoblast physiology through affecting the production and secretion of CGRP. The capsaicin-activated neuronal TRPV1-CGRP axis could enhance the proliferation, migration and differentiation of osteoblasts (p < 0.05). Furthermore, we found that the promoting role of neuronal TRPV1 in osteogenesis was associated with Hippo signaling pathway, reflected by the phosphorylation protein level of large tumor suppressor 1 (LATS1), MOB kinase activator 1 (MOB1) and Yes-associated protein (YAP), as well as the subcellular location of YAP. Our study clarified the effects and intrinsic mechanisms of neuronal TRPV1 on bone defect repair, which might offer us a therapeutic implication for bone disorders.

TRPV1 activation in human Langerhans cells and T cells inhibits mucosal HIV-1 infection via CGRP-dependent and independent mechanisms

Upon its mucosal transmission, HIV type 1 (HIV-1) rapidly targets genital antigen-presenting Langerhans cells (LCs), which subsequently transfer infectious virus to CD4+ Tcells. We previously described an inhibitory neuroimmune cross talk, whereby calcitonin gene-related peptide (CGRP), a neuropeptide secreted by peripheral pain-sensing nociceptor neurons innervating all mucosal epithelia and associating with LCs, strongly inhibits HIV-1 transfer. As nociceptors secret CGRP following the activation of their Ca2+ ion channel transient receptor potential vanilloid 1 (TRPV1), and as we reported that LCs secret low levels of CGRP, we investigated whether LCs express functional TRPV1. We found that human LCs expressed mRNA and protein of TRPV1, which was functional and induced Ca2+ influx following activation with TRPV1 agonists, including capsaicin (CP). The treatment of LCs with TRPV1 agonists also increased CGRP secretion, reaching its anti-HIV-1 inhibitory concentrations. Accordingly, CP pretreatment significantly inhibited LCs-mediated HIV-1 transfer to CD4+ Tcells, which was abrogated by both TRPV1 and CGRP receptor antagonists. Like CGRP, CP-induced inhibition of HIV-1 transfer was mediated via increased CCL3 secretion and HIV-1 degradation. CP also inhibited direct CD4+ Tcells HIV-1 infection, but in CGRP-independent manners. Finally, pretreatment of inner foreskin tissue explants with CP markedly increased CGRP and CCL3 secretion, and upon subsequent polarized exposure to HIV-1, inhibited an increase in LC-Tcell conjugate formation and consequently Tcell infection. Our results reveal that TRPV1 activation in human LCs and CD4+ Tcells inhibits mucosal HIV-1 infection, via CGRP-dependent/independent mechanisms. Formulations containing TRPV1 agonists, already approved for pain relief, could hence be useful against HIV-1.

Expanding Applications of CGRP Modification for Post-traumatic Brain Injury Symptom Control (P7-1.001)

<h3>Objective:</h3> To demonstrate effective use of calcitonin gene-related peptide (CGRP) modulating medications for post-traumatic brain injury (TBI) symptoms in a diverse group of patients and illuminate the potential utility of CGRP medications for regular use after TBI. <h3>Background:</h3> The mechanism by which CGRP results in headache and migraine spectrum symptoms has been established. CGRP is recently understood to remain elevated in rat models after concussion. These findings portend implications for application of CGRP modification in human patients with TBI. Persistent Postural-Perceptual Dizziness (3PD), is recently becoming better understood. Because of its close association with migraine headache, 3PD is also likely a derangement of CGRP and may benefit from medications for CGRP modulation. <h3>Design/Methods:</h3> Patient consent was obtained to share de-identified patient information and outcomes. Case management is ongoing and will be presented in depth and include relevant imaging, testing results, and graphical representation of symptom changes following treatment initiation (Figures 1–5). <h3>Results:</h3> Five patients are presented: Two patients surviving moderate TBI and three patients with prolonged symptoms after concussion were all identified as having chronic migraine by a neurologist and 3PD by a neuro-otologist (Table 1). These patients were treated with CGRP modifying medications with successful resolution of migraine and 3PD symptoms. <h3>Conclusions:</h3> Clinicians can use preliminary findings about CGRP secretion in animal and human models to predict symptom outcomes in at-risk patients and treat chronic concussion symptoms if they occur. We present five patients who now have reduced or eliminated chronic concussion symptoms after initiating medications that modulate CGRP and explain how these experiences can translate into our daily practices when caring for patients with TBI. <b>Disclosure:</b> Mrs. Wang has nothing to disclose. Miss Samdrup has nothing to disclose. Paige Buddenhagen has nothing to disclose. Dr. Essad has nothing to disclose.

Three-dimensional visualization of neural networks inside bone by Osteo-DISCO protocol and alteration of bone remodeling by surgical nerve ablation

Bone is one of the largest organ systems in humans and is considered to regulate whole-body homeostasis in cooperation with other organs. We have previously reported that a sympathetic or sensory nervous system inside bone regulates bone homeostasis. However, the detailed regulatory mechanism, including the distribution of nerves inside bone, remains unknown. Although a two-dimensional histological analysis has been widely used to evaluate the structure of nerves or blood vessels, the actual structure is more complex, suggesting that it should be evaluated three-dimensionally. Here, we established a novel bone tissue clearing technique (Osteo-DISCO) for murine bones which enabled us to visualize the detailed distribution of nerves or blood vessels inside bone. Interestingly, we found that there is a specific nerve entry site in each long bone and that surgical ablation of the specific nerve fibers entering bone tissue led to decreased bone formation and impaired bone regeneration. Furthermore, we revealed that the administration of calcitonin gene-related peptide (CGRP), which is primarily released from sensory nerves, suppressed the bone loss caused by surgical nerve ablation. An in vitro study also indicated that CGRP directly promotes osteoblast activity, suggesting that sensory nerves inside bone can regulate osteogenesis via the secretion of CGRP.

Nutrition and Calcitonin Gene Related Peptide (CGRP) in Migraine.

Targeting calcitonin gene-related peptide (CGRP) and its receptor by antibodies and antagonists was a breakthrough in migraine prevention and treatment. However, not all migraine patients respond to CGRP-based therapy and a fraction of those who respond complain of aliments mainly in the gastrointestinal tract. In addition, CGRP and migraine are associated with obesity and metabolic diseases, including diabetes. Therefore, CGRP may play an important role in the functioning of the gut-brain-microflora axis. CGRP secretion may be modulated by dietary compounds associated with the disruption of calcium signaling and upregulation of mitogen-activated kinase phosphatases 1 and 3. CGRP may display anorexigenic properties through induction of anorexigenic neuropeptides, such as cholecystokinin and/or inhibit orexigenic neuropeptides, such as neuropeptide Y and melanin-concentrating hormone CH, resulting in the suppression of food intake, functionally coupled to the activation of the hypothalamic 3',5'-cyclic adenosine monophosphate. The anorexigenic action of CGRP observed in animal studies may reflect its general potential to control appetite/satiety or general food intake. Therefore, dietary nutrients may modulate CGRP, and CGRP may modulate their intake. Therefore, anti-CGRP therapy should consider this mutual dependence to increase the efficacy of the therapy and reduce its unwanted side effects. This narrative review presents information on molecular aspects of the interaction between dietary nutrients and CGRP and their reported and prospective use to improve anti-CGRP therapy in migraine.

Grape seed extract suppresses calcitonin gene-related peptide secretion and upregulates expression of GAD 65/67 and GABAB receptor in primary trigeminal ganglion cultures.

The trigeminal ganglion is implicated in the underlying pathology of migraine and temporomandibular joint disorders (TMD), which are orofacial pain conditions involving peripheral and central sensitization. The neuropeptide calcitonin gene-related peptide (CGRP) is synthesized in some trigeminal ganglion neurons, and its release promotes inflammation, peripheral and central sensitization, and pain signaling. Recent studies in preclinical migraine and TMD models provide evidence that dietary supplementation with grape seed extract (GSE) inhibits trigeminal pain signaling. The goal of this study was to investigate the cellular mechanisms by which GSE modulates primary trigeminal ganglion cultures. The effect of GSE on CGRP secretion was determined by radioimmunoassay. To determine if GSE effects involved modulation of CGRP or the GABAergic system, expression of CGRP, GAD 65 and 67, GABAA receptor, and GABAB1 and GABAB2 receptor subunits were investigated by immunocytochemistry. GSE significantly inhibited basal CGRP secretion but did not alter neuronal CGRP expression. GAD 65 and 67 expression levels in neurons were significantly increased in response to GSE. While GSE did not cause a change in the neuronal expression of GABAA, GSE significantly increased GABAB1 expression in neurons, satellite glial cells, and Schwann cells. GABAB2 expression was significantly elevated in satellite glia and Schwann cells. These findings support the notion that GSE inhibition of basal CGRP secretion involves increased neuronal GAD 65 and 67 and GABAB receptor expression. GSE repression of CGRP release coupled with increased GABAB1 and GABAB2 glial cell expression would be neuroprotective by suppressing neuronal and glial excitability in the trigeminal ganglion.

The endogenous neuropeptide calcitonin gene-related peptide after spontaneous subarachnoid hemorrhage-A potential psychoactive prognostic serum biomarker of pain-associated neuropsychological symptoms.

BackgroundThe pronociceptive neuromediator calcitonin gene-related peptide (CGRP) is associated with pain transmission and modulation. After spontaneous subarachnoid hemorrhage (sSAH), the vasodilatory CGRP is excessively released into cerebrospinal fluid (CSF) and serum and modulates psycho-behavioral function. In CSF, the hypersecretion of CGRP subacutely after good-grade sSAH was significantly correlated with an impaired health-related quality of life (hrQoL). Now, we prospectively analyzed the treatment-specific differences in the secretion of endogenous CGRP into serum after good-grade sSAH and its impact on hrQoL.MethodsTwenty-six consecutive patients (f:m = 13:8; mean age 50.6 years) with good-grade sSAH were enrolled (drop out n = 5): n = 9 underwent endovascular aneurysm occlusion, n = 6 microsurgery, and n = 6 patients with perimesencephalic SAH received standardized intensive medical care. Plasma was drawn daily from day 1 to 10, at 3 weeks, and at the 6-month follow-up (FU). CGRP levels were determined with competitive enzyme immunoassay in duplicate serum samples. All patients underwent neuropsychological self-report assessment after the onset of sSAH (t1: day 11–35) and at the FU (t2).ResultsDuring the first 10 days, the mean CGRP levels in serum (0.470 ± 0.10 ng/ml) were significantly lower than the previously analyzed mean CGRP values in CSF (0.662 ± 0.173; p = 0.0001). The mean serum CGRP levels within the first 10 days did not differ significantly from the values at 3 weeks (p = 0.304). At 6 months, the mean serum CGRP value (0.429 ± 0.121 ng/ml) was significantly lower compared to 3 weeks (p = 0.010) and compared to the first 10 days (p = 0.026). Higher mean serum CGRP levels at 3 weeks (p = 0.001) and at 6 months (p = 0.005) correlated with a significantly poorer performance in the item pain, and, at 3 weeks, with a higher symptom burden regarding somatoform syndrome (p = 0.001) at t2.ConclusionOur study reveals the first insight into the serum levels of endogenous CGRP in good-grade sSAH patients with regard to hrQoL. In serum, upregulated CGRP levels at 3 weeks and 6 months seem to be associated with a poorer mid-term hrQoL in terms of pain. In migraineurs, CGRP receptor antagonists have proven clinical efficacy. Our findings corroborate the potential capacity of CGRP in pain processing.

Nociceptor Neurons are Involved in the Host Response to Escherichia coli Urinary Tract Infections.

PurposeUrinary tract infections (UTIs) can evoke a rapid host immune response leading to bladder inflammation and epithelial damage. Neuroimmune interactions are critical for regulating immune function in mucosal tissues. Yet the role of nociceptor neurons in bladder host defense has not been well defined. This study aimed to explore the interaction between nociceptor neurons and bladder immune system during UTIs.MethodsIn this study, whether uropathogenic Escherichia coli (UPEC) and lipopolysaccharide (LPS) can directly stimulate nociceptor neurons was detected. Female C57BL/6J mice were treated with high dose of capsaicin, a high-affinity TRPV1 agonist, to ablate nociceptor neurons. Bladder inflammation, barrier epithelial function and bladder immune cell infiltration were assessed after UPEC infection. The level of neuropeptide calcitonin gene-related peptide (CGRP) in infected bladder was detected. Furthermore, the effects of CGRP on neutrophils and macrophages were evaluated both in vitro and in vivo.ResultsWe found that UPEC and its pathogenic factor LPS could directly excite nociceptor neurons, releasing CGRP into infected bladder, which suppressed the recruitment of neutrophils, the polarization of macrophages and the killing function of UPEC. Both Botulinum neurotoxin A (BoNT/A) and BIBN4096 (CGRP antagonism) blocked neuronal inhibition and prevented against UPEC infection.ConclusionThe present study showed a novel mechanism by which UPEC stimulated the secretion of CGRP from nociceptor neurons to suppress innate immunity.

Functional tuning of commensal-specific lymphocytes by nociceptive sensory neurons

Abstract The somatosensory nervous system surveils external stimuli at barrier tissues, regulating innate immune cells under infection and inflammation. The roles of nociceptive nerves in homeostatic adaptive immunity to the microbiota, however, remain elusive. Here, we identified a novel mechanism for direct neuro-immune interaction between commensal-specific T lymphocytes and skin-innervating nociceptive neurons through secretion of calcitonin gene-related peptide (CGRP). We observed upregulation of the CGRP co-receptor, receptor activity modifying protein 1 (RAMP1), in T lymphocytes induced by topical colonization of the human skin commensal Staphylococcus epidermidis, but not in T cell populations elicited by cutaneous infection or inflammation. Utilizing intravital imaging, we observed that commensal-specific T cells interact intimately and dynamically with skin nociceptive nerves in a CGRP-dependent manner. Importantly, CGRP secreted from nociceptors acts directly on commensal-specific T cells via RAMP1 to regulate their accumulation in the tissues, cytokine production and motility in vivo. Activation or inhibition of nociceptive neurons functionally tune commensal-specific T cells and optimize their responses to ensuing heterologous infections or damaging challenges in the skin. The ability of the somatosensory neurons to participate in the highly specific and potentially long-lasting adaptive immune response to the microbiota underscores the functional versatility and plasticity of commensal-specific T lymphocytes that can be swiftly tuned to diverse arrays of sensory modalities ranging from thermosensation to noxious pain under steady state and pathology. Supported by Damon Runyon Cancer Research Foundation

Cutaneous nerve fibers participate in the progression of psoriasis by linking epidermal keratinocytes and immunocytes.

Recent studies have illustrated that psoriatic lesions are innervated by dense sensory nerve fibers. Psoriatic plaques appeared to improve after central or peripheral nerve injury. Therefore, the nervous system may play a vital role in psoriasis. We aimed to clarify the expression of nerve fibers in psoriasis and their relationship with immune cells and keratinocytes, and to explore the effect of skin nerve impairment. Our results illustrated that nerve fibers in psoriatic lesions increased and were closely innervated around immune cells and keratinocytes. RNA-seq analysis showed that peripheral sensory nerve-related genes were disrupted in psoriasis. In spinal cord hemi-section mice, sensory impairment improved psoriasiform dermatitis and inhibited the abnormal proliferation of keratinocytes. Botulinum toxin A alleviated psoriasiform dermatitis by inhibiting the secretion of calcitonin gene-related peptide. Collectively, cutaneous nerve fibers participate in the progression of psoriasis by linking epidermal keratinocytes and immunocytes. Neurological intervention may be a new treatment strategy for psoriasis.

Effect of electroacupuncture on pulmonary neuroendocrine cells and secretion of neuroactive substances in lung of COPD rats

To observe the effect of electroacupuncture (EA) at "Zusanli" (ST36) and "Feishu" (BL13) on the activation and secretion of calcitonin gene-related peptide (CGRP) and 5-hydroxytryptamine (5-HT) of pulmonary neuroendocrine cells (PNECs) and inflammatory response in rats with chronic obstructive pulmonary disease (COPD), so as to explore its underlying mechanisms in treating COPD. Male SD rats were randomly divided into normal control, COPD model and EA groups, with 7 rats in each group. The COPD model was established by forced inhale of cigarette smoke for 1 h in a self-made box (1 m×1 m×1 m in volume), twice daily for 12 weeks. EA (4 Hz/20 Hz, 1-3 mA) was applied at bilateral ST36 and BL13 acupoints for 30 min, once a day for 14 consecutive days. The pulmonary function including the forced vital capacity (FVC), forced expiratory volume at 0.1 second (FEV0.1), FEV0.3, FEV0.1/FVC and FEV0.3/FVC was detected using a lung function analyzer for small animals. The lung tissue was sampled for observing histopathological changes by using H.E. staining, for observing expression and distribution of PNECs by Grimelius silver staining, and for detecting the immunoactivity (integrated optical density) of CGRP and 5-HT by using immunohistochemistry. The contents of CGRP, 5-HT, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1) in the bronchoalveolar lavage fluid (BALF) and lung tissue were detected by ELISA, and the correlations between TNF-α and CGRP, IL-1β and CGRP, TNF-α and 5-HT, and IL-1β and 5-HT levels were analyzed. The mRNA and protein expression levels of nerve fiber markers of CGRP and purinergic receptor P2X ligand gated ion channel 3 (P2X3) which dominate PNECs in the lung tissue were detected by real-time fluorescence quantitative PCR and Western blot, respectively. Compared with the normal control group, the levels of FVC, FEV0.1, FEV0.3, and the ratios of FEV0.1/FVC and FEV0.3/FVC were significantly decreased (P<0.05, P<0.01), while the immunoactivity of PNECs, CGRP and 5-HT, the contents of CGRP, 5-HT, TNF-α, IL-1β and TGF-β1 in the BALF and lung tissue, and the expression levels of CGRP and P2X3 mRNAs and proteins in the lung tissue significantly increased in the COPD model group (P<0.01, P<0.05). Following EA intervention, both the increased and decreased levels of all the indexes mentioned above were reversed (P<0.05, P<0.01) except FEV0.3. H.E. staining showed severe deformed bronchial lumen with thickened wall and alveolar septum, and obvious inflammatory cell infiltration and reduced number of alveolar lumen fusion in the COPD model group, which was mild in the EA group. A positive correlation was found between TNF-α and CGRP, IL-1β and CGRP, TNF-α and 5-HT,IL-1β and 5-HT levels in both BALF and lung tissues (P<0.01). EA at ST36 and BL13 can improve lung function and reduce inflammatory response in COPD rats, which may be related to its function in inhibiting the activation of PNECs and release of neuroactive substances.

Senso-Immunologic Prospects for Complex Regional Pain Syndrome Treatment.

Complex regional pain syndrome (CRPS) is a chronic pain syndrome that occurs in tissue injuries as the result of surgery, trauma, or ischemia. The clinical features of this severely painful condition include redness and swelling of the affected skin. Intriguingly, it was recently suggested that transient receptor potential ankyrin 1 (TRPA1) is involved in chronic post-ischemia pain, a CRPS model. TRPA1 is a non-selective cation channel expressed in calcitonin gene-related peptide (CGRP)-positive primary nociceptors that becomes highly activated in ischemic conditions, leading to the generation of pain. In this review, we summarize the history of TRPA1 and its involvement in pain sensation, inflammation, and CRPS. Furthermore, bone atrophy is also thought to be a characteristic clinical sign of CRPS. The altered bone microstructure of CRPS patients is thought to be caused by aggravated bone resorption via enhanced osteoclast differentiation and activation. Although TRPA1 could be a target for pain treatment in CRPS patients, we also discuss the paradoxical situation in this review. Nociceptor activation decreases the risk of bone destruction via CGRP secretion from free nerve endings. Thus, TRPA1 inhibition could cause severe bone atrophy. However, the suitable therapeutic strategy is controversial because the pathologic mechanisms of bone atrophy in CRPS are unclear. Therefore, we propose focusing on the remission of abnormal bone turnover observed in CRPS using a recently developed concept: senso-immunology.

Nociceptive nerves regulate haematopoietic stem cell mobilization.

Haematopoietic stem cells (HSCs) reside in specialized microenvironments in the bone marrow (BM), often referred to as “niches”, which represent complex regulatory milieux influenced by multiple cellular constituents, including nerves1,2. Although sympathetic nerves regulate the HSC niche3-6, the contribution of nociceptive neurons in the BM remains unclear. Here we show that nociceptive nerves are required for enforced HSC mobilization and collaborate with sympathetic nerves for HSC maintenance in BM. Nociceptor neurons drive granulocyte colony-stimulating factor (G-CSF)-induced HSC mobilization via the secretion of calcitonin gene-related peptide (CGRP). Unlike sympathetic nerves which regulate HSCs indirectly via the niche3,4,6, CGRP acts directly on HSCs via the receptor activity modifying protein-1 (RAMP1) and calcitonin-receptor-like receptor (CALCRL), to promote egress by activating Gαs/Adenylyl cyclase/cAMP pathway. Remarkably, the ingestion of food containing capsaicin (a natural component of chili peppers), significantly enhanced HSC mobilization. Thus, targeting the nociceptive nervous system is a novel strategy to improve the HSC yield for stem cell-based therapeutics.

Calcitonin gene‑related peptide‑mediated pharmacological effects in cardiovascular and gastrointestinal diseases (Review).

Calcitonin gene‑related peptide (CGRP) is the predominant neurotransmitter located in sensory nerves. This peptide is extensively distributed in central and peripheral tissues. CGRP causes relaxation of cardiovascular smooth muscle cells and confers protection against ischaemic myocardium and cardiac remodeling. The pharmacological effects of nitroglycerine and rutaecarpine have been demonstrated to be associated with an increase in the synthesis and release of CGRP. In the gastrointestinal tissues, CGRP participates in the regulation of gastrointestinal function, and exerts protective effects on gastric mucosa. Rutaecarpine, capsaicin and its derivatives, such as evodiamine, decrease gastric mucosal damage induced by several factors, including increased synthesis and release of CGRP. Taken together, this review focuses on the pharmacological effects of several CGRP related canonical drugs and suggests that synthesis and secretion of CGRP exhibit significant therapeutic effects in the occurrence and development of cardiovascular and gastrointestinal diseases.

Endogenous calcitonin gene-related peptide in cerebrospinal fluid and early quality of life and mental health after good-grade spontaneous subarachnoid hemorrhage\u2014a feasibility series

The vasodilatory calcitonin gene-related peptide (CGRP) is excessively released after spontaneous subarachnoid hemorrhage (sSAH) and modulates psycho-behavioral function. In this pilot study, we prospectively analyzed the treatment-specific differences in the secretion of endogenous CGRP into cerebrospinal fluid (CSF) during the acute stage after good-grade sSAH and its impact on self-reported health-related quality of life (hrQoL). Twenty-six consecutive patients (f:m = 13:8; mean age 50.6 years) with good-grade sSAH were enrolled (drop out 19% (n = 5)): 35% (n = 9) underwent endovascular aneurysm occlusion, 23% (n = 6) microsurgery, and 23% (n = 6) of the patients with perimesencephalic SAH received standardized intensive medical care. An external ventricular drain was inserted within 72 h after the onset of bleeding. CSF was drawn daily from day 1–10. CGRP levels were determined via competitive enzyme immunoassay and calculated as “area under the curve” (AUC). All patients underwent a hrQoL self-report assessment (36-Item Short Form Health Survey (SF-36), ICD-10-Symptom-Rating questionnaire (ISR)) after the onset of sSAH (t1: day 11–35) and at the 6-month follow-up (t2). AUC CGRP (total mean ± SD, 5.7 ± 1.8 ng/ml/24 h) was excessively released into CSF after sSAH. AUC CGRP levels did not differ significantly when dichotomizing the aSAH (5.63 ± 1.77) and pSAH group (5.68 ± 2.08). aSAH patients revealed a higher symptom burden in the ISR supplementary item score (p = 0.021). Multiple logistic regression analyses corroborated increased mean levels of AUC CGRP in CSF at t1 as an independent prognostic factor for a significantly higher symptom burden in most ISR scores (compulsive-obsessive syndrome (OR 5.741, p = 0.018), anxiety (OR 7.748, p = 0.021), depression (OR 2.740, p = 0.005), the supplementary items (OR 2.392, p = 0.004)) and for a poorer performance in the SF-36 physical component summary score (OR 0.177, p = 0.001). In contrast, at t2, CSF AUC CGRP concentrations no longer correlated with hrQoL. To the best of our knowledge, this study is the first to correlate the levels of endogenous CSF CGRP with hrQoL outcome in good-grade sSAH patients. Excessive CGRP release into CSF may have a negative short-term impact on hrQoL and emotional health like anxiety and depression. While subacutely after sSAH, higher CSF levels of the vasodilator CGRP are supposed to be protective against vasospasm-associated cerebral ischemia, from a psychopathological point of view, our results suggest an involvement of CSF CGRP in the dysregulation of higher integrated behavior.

Majie cataplasm provides a shield against asthmatic punch from the neuroimmune system

Asthma poses a threat to human health, and its pathogenesis is closely related to the neuroimmune system. Majie cataplasm can not only regulate the immune system but also the nervous system in asthma patients for its components. We speculate that Majie cataplasm may relieve asthmatic patients with sensitivity to hormone or not by regulating the body's neuroimmune system. MethodsIn this experiment, a mouse model of asthma was well established by ovalbumin. The lung function of animals was examined and pathological changes in the lung tissue were assessed by hematoxylin-eosin staining. Serum immunoglobulin E (IgE), calcitonin gene-related peptide (CGRP) and neurokinin A (NKA) were measured by ELISA. The location of CGRP, CD3 and neutrophil in lung tissue and their expressions were detected by immunofluorescence staining. In addition, contents of CGRP mRNA, Substance P (SP) mRNA, interleukin (IL)-17 mRNA and interleukin(IL)-13 mRNA were detected by quantitative polymerase chain reaction. ResultsCompared with the asthma model group, Majie cataplasm and dexamethasone can not only equivalently relieve airway hyperresponsiveness, but also make the content of serum IgE reduced. In addition, they can lower the content of serum CGRP and NKA after OVA stimulation, and this effect was more obvious for Majie cataplasm. Our results also showed that Majie Cataplasm and dexamethasone could inhibit the secretion of CGRP and the infiltration of T lymphocytes together with neutrophils in lung tissue and reduce expressions of CGRP mRNA, SP mRNA, IL-17 mRNA and IL-13 mRNA in lung tissue. ConclusionMajie cataplasm effectively relieves expressions of neuropeptides such as CGRP, reduces the infiltration of immune cells in lung tissue, regulates the body's neuroimmune system, and has a therapeutic potential for both Th2 asthma and neutrophilic asthma.

CGRP derived from cardiac fibroblasts is an endogenous suppressor of cardiac fibrosis.

Aberrant activation of cardiac fibroblasts leads to cardiac fibrosis, and evolving evidences suggest that endogenous bioactive substances derived from cardiac fibroblasts regulate cardiac fibroblasts activation in an autocrine/paracrine manner. Here we first presented evidence that cardiac fibroblasts can synthesize and secrete calcitonin gene-related peptide (CGRP), therefore, this study aimed to investigate the role of cardiac fibroblasts-derived CGRP in cardiac fibroblasts activation and its regulative mechanism. The abundantly expression of CGRP in rat, mouse, and human myocardium allowed us to explore the cellular origin of CGRP, and found that the cardiac CGRP was mainly derived from cardiac fibroblasts. Activating TRPA1 with a specific agonist allyl isothiocyanate promoted the synthesis and secretion of CGRP, as well as intracellular Ca2+. These effects were reversed by TRPA1-specific antagonist HC030031 and Ca2+ chelator BAPTA-AM. TGF-β1 was applied to induce the activation of cardiac fibroblasts, and found that TGF-β1 can increase the mRNA expression and secretion levels of CGRP in cardiac fibroblasts. Either CGRP8-37 (CGRP receptor antagonist) or α-CGRP small interfering RNA (siRNA) aggravated TGF-β1-induced proliferation, differentiation, collagen production, and instigated inflammation in cardiac fibroblasts. Moreover, TGF-β1-induced NF-κB activation including IκBα phosphorylation and p65 nuclear translocation were also promoted by CGRP8-37 and α-CGRP siRNA. NF-κB inhibitor pyrrolidinedithiocarbamate ammonium (PDTC) reversed the effects of CGRP8-37 on NF-κB activation. The promotive effects of CGRP8-37 on TGF-β1-induced activation of cardiac fibroblasts were all reversed by PDTC. Monocrotaline (MCT) induces pulmonary arterial hypertension, progressively leading to right ventricular fibrosis. This model of cardiac fibrosis was developed here to test the potentially beneficial effects of TRPA1 activation in vivo. The non-toxic TRPA1 agonist Cinnamaldehyde (CA) inhibited MCT-induced elevation in right ventricle systolic pressure, RV/LV + S, and right ventricular collagen accumulation, as well as down-regulation of CGRP. CA increased the synthesis and secretion of CGRP, and inhibited TGF-β1-induced activation in cardiac fibroblasts. Our data suggested an autocrine role for cardiac fibroblasts-derived CGRP in suppressing activation of cardiac fibroblasts through inhibiting NF-κB activation. Increasing autocrine CGRP by activating TRPA1 can ameliorate cardiac fibrosis. These findings support the notion that CGRP derived from cardiac fibroblasts is an endogenous suppressor of cardiac fibrosis.