Neurokinin-1 Receptor Research Articles

Substance P promotes transforming growth factor-β-induced collagen synthesis in human corneal fibroblasts.

Corneal fibroblasts maintain homeostasis of the corneal stroma by mediating the synthesis and degradation of extracellular collagen, and these actions are promoted by transforming growth factor-β (TGF-β) and interleukin-1β (IL-1β), respectively. The cornea is densely innervated with sensory nerve fibers that are not only responsible for sensation but also required for physiological processes such as tear secretion and wound healing. Loss or dysfunction of corneal nerves thus impairs corneal epithelial wound healing and can lead to neurotrophic keratopathy. The sensory neurotransmitter substance P (SP) promotes corneal epithelial wound healing by enhancing the stimulatory effects of growth factors and fibronectin. We have now investigated the role of SP in collagen metabolism mediated by human corneal fibroblasts in culture. Although SP alone had no effect on collagen synthesis or degradation by these cells, it promoted the stimulatory effect of TGF-β on collagen type I synthesis without affecting that of IL-1β on the expression of matrix metalloproteinase-1. This effect of SP on TGF-β-induced collagen synthesis was accompanied by activation of p38 mitogen-activated protein kinase (MAPK) signaling and was attenuated by pharmacological inhibition of p38 or of the neurokinin-1 receptor. Our results thus implicate SP as a modulator of TGF-β-induced collagen type I synthesis by human corneal fibroblasts, and they suggest that loss of this function may contribute to the development of neurotrophic keratopathy.NEW & NOTEWORTHY This study investigates the role of substance P (SP) in collagen metabolism mediated by human corneal fibroblasts in culture. We found that, although SP alone had no effect on collagen synthesis or degradation by corneal fibroblasts, it promoted the stimulatory effect of transforming growth factor-β on collagen type I synthesis without affecting that of interleukin-1β on the expression of matrix metalloproteinase-1.

NK3R signalling in the posterodorsal medial amygdala is involved in stress-induced suppression of pulsatile LH secretion in female mice.

Psychosocial stress negatively impacts reproductive function by inhibiting pulsatile luteinizing hormone (LH) secretion. The posterodorsal medial amygdala (MePD) is responsible in part for processing stress and modulating the reproductive axis. Activation of the neurokinin 3 receptor (NK3R) suppresses the gonadotropin-releasing hormone (GnRH) pulse generator, under hypoestrogenic conditions, and NK3R activity in the amygdala has been documented to play a role in stress and anxiety. We investigate whether NK3R activation in the MePD is involved in mediating the inhibitory effect of psychosocial stress on LH pulsatility in ovariectomised female mice. First, we administered senktide, an NK3R agonist, into the MePD and monitored the effect on pulsatile LH secretion. We then delivered SB222200, a selective NK3R antagonist, intra-MePD in the presence of predator odour, 2,4,5-trimethylthiazole (TMT) and examined the effect on LH pulses. Senktide administration into the MePD dose-dependently suppresses pulsatile LH secretion. Moreover, NK3R signalling in the MePD mediates TMT-induced suppression of the GnRH pulse generator, which we verified using a mathematical model. The model verifies our experimental findings: (i) predator odour exposure inhibits LH pulses, (ii) activation of NK3R in the MePD inhibits LH pulses and (iii) NK3R antagonism in the MePD blocks stressor-induced inhibition of LH pulse frequency in the absence of ovarian steroids. These results demonstrate for the first time that NK3R neurons in the MePD mediate psychosocial stress-induced suppression of the GnRH pulse generator.

Abstract 2570: Gastric cancer with high neuron infiltration was associated with enhanced epithelial-to-mesenchymal transition, angiogenesis and poor clinical outcomes

Abstract Introduction: Neurons within the tumor microenvironment of gastric cancer (GC), as identified through immunohistochemistry, have been reported to be associated with worse overall survival (OS) of GC patients. However, histology-based analyses have limitations in quantifying nerve cells and investigating the underlying biology. Thus, we aim to study the clinical significance of intratumoral nerve cells in GC using computational deconvolution of transcriptomes from bulk tumors. Methods: Total of 807 GC patients from two independent cohorts (TCGA; n = 375, GSE84437; n = 432) were included, encompassing both clinical and transcriptomic profiles. The neuron infiltration fraction was determined using the xCell algorithm. Results: GC with high neuron infiltration was associated with high expressions of neurotransmitter receptors; beta-adrenaline, dopamine, muscarinic acetylcholine, and neurokinin receptors in TCGA cohort (all p < 0.02). It was associated with reduced mutation rate and increased intratumoral heterogeneity (all p ≦ 0.002), as well as less immune response; interferon-alpha and interferon-gamma, and with low infiltration of immune cells; CD4 memory, T-helper 1, M1 and M2 macrophages, and NK cells (all p ≦ 0.02). Further, neuron highly infiltrated GC enriched Epithelial-to-Mesenchymal Transition and Angiogenesis gene sets and had higher lymphatic and microvessel endothelial cells and pericyte infiltrations (all p ≦ 0.001). Conversely, GC with high neuron infiltration showed an inverse relationship with cell proliferation-related gene sets; E2F Targets, G2M Checkpoint, and MYC Targets v1 and v2, and had lower Ki67 gene expression (FDR < 0.25 and p < 0.001, respectively). High neuron infiltration in GC was associated with worse patient OS in TCGA cohort, which was validated in GSE84437 cohort (both p < 0.05). It was an independent prognostic factor of OS in both univariate and multivariate Cox-regression analysis in the TCGA cohort (hazard ratio [HR]: 1.46; 95% confidence interval [CI]: 1.01 to 2.12; p = 0.045 and [HR]:1.54; 95% CI: 1.05 to 2.26; p = 0.026). Conclusion: Our research indicates that high infiltration of neurons in GC correlates with high expressions of neurotransmitter receptors, high intratumoral heterogeneity, less immune response and immune cell infiltrations, and less cell proliferation. It enriched EMT and angiogenesis which may explain its association with worse patient survival. Citation Format: Kohei Chida, Masanori Oshi, Arya Mariam Roy, Jun Arima, Pia Sharma, Gabriella Kim Mann, Itaru Endo, Kenichi Hakamada, Kazuaki Takabe. Gastric cancer with high neuron infiltration was associated with enhanced epithelial-to-mesenchymal transition, angiogenesis and poor clinical outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2570.

Abstract 5995: How FDA-approved drug, Aprepitant, induces immunogenic death of cancer cells

Abstract Aprepitant is a long-standing FDA approved anti-nausea drug, recently re-purposed as an early-stage anticancer agent; how aprepitant kills cancer cells was not well studied. We find that aprepitant kills human and mouse cancer cells by hyperactivating the stress response pathway, the anticipatory unfolded protein response (a-UPR), thereby inducing immune cell activating necrotic cell death. Aprepitant is a small molecule neurokinin-1 receptor (NK-1R) antagonist widely used to prevent nausea and vomiting in cancer patients undergoing chemotherapy. Recently aprepitant has shown promise in mouse xenograft studies of colon, lung and pancreatic cancer and melanoma. Since aprepitant was thought to trigger release of calcium stored in the lumen of the endoplasmic reticulum, the step that we showed triggers hyperactivation of the a-UPR by ErSO family anticancer agents, we explored the role of the a-UPR in aprepitant action. Aprepitatnt robustly activates the PERK arm of the UPR increasing p-PERK and peIF2α, inhibiting protein synthesis. Notably, aprepitant treatment results in ATP depletion and activation of AMPK. Aprepitant induced rapid cell death was not blocked by apoptosis inhibitors or necroptosis inhibitors. In both standard 2-dimensional cell culture and 3-dimensional organoid culture aprepitant-treated breast cancer cells displayed typical features of necrotic cell death, including cell swelling, membrane rupture, and cytoplasmic vacuolization. Cell death by necrosis and membrane rupture leads to release of immune cell activating cell contents termed damage-associated molecular patterns (DAMPs). Aprepitant treatment induces release of the classic DAMPs, HMGB1 and ATP and medium from aprepitant-treated breast cancer cells enhances migration of differentiated human THP-1 macrophage. Thus aprepitant and other necrosis inducing therapies elicit immunogenic cell death (ICD) and may have the potential to enhance adjuvant immunotherapy. Genome-wide CRISPR screens with negative selection against aprepitant and other studies are being used to explore the pathways of aprepitant induced cell death and evaluate its therapeutic efficacy. Since FDA-approved aprepitant has been widely used for many years, identifying its pathway of action will both accelerate its clinical transition as an anticancer agent and help identify patients whose genetic profiles make them most likely to benefit from aprepitant therapy. Citation Format: Xinyi Dai, Junyao Zhu, Sofia Perry, Qianjin Jiang, David J. Shapiro. How FDA-approved drug, Aprepitant, induces immunogenic death of cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5995.

Retrospective analysis of real-world prescribing data for managing cisplatin-based chemotherapy-induced nausea and vomiting in China.

The current utilization of neurokinin-1 receptor antagonists (NK1RAs) and the impact of updated guidelines on prescription patterns of antiemetic drugs among Chinese patients receiving highly emetogenic chemotherapy (HEC) remain undetermined. This study aims to analyze the present situation of Chinese cancer patients using antiemetic drugs and assess the appropriateness of antiemetic regimens. Prescription data were collected between January 2015 and December 2020 from cancer patients receiving cisplatin-based chemotherapy at 76 hospitals in six major cities in China. Trends in the use of antiemetic drugs, prescribing patterns and adherence to antiemetic guidelines were assessed. Among the 108,611 patients included in this study, 6 classes and 17 antiemetic drugs were identified as monotherapy or combination therapy in 93,872 patients (86.4%), whereas 14,739 patients (13.6%) were administered no antiemetic treatment. 5-hydroxytryptamine 3 receptor antagonists (5-HT3RAs) and glucocorticoids were the two most frequently used classes of antiemetics, followed by metoclopramide. NK1RAs were underused across the six cities, only 9332 (8.6%) and 1655 (1.5%) cisplatin-based treatments were prescribed aprepitant and fosaprepitant, respectively. Prescriptions of olanzapine and lorazepam were very low throughout the study period. In prescribing patterns of antiemetic drugs, dual combination regimens were the most common (40.0%), followed by triple combination therapy and monotherapy (25.8% and 15.1%, respectively). Overall, the adherence to antiemetic guidelines for patients undergoing cisplatin-based regimens was only 8.1% due to inadequate prescription of antiemetic drugs. Finally, our study also revealed that 5-HT3RAs and glucocorticoids were overprescribed in 8.8% and 1.6% of patients, respectively. The current study reveals suboptimal utilization of recommended antiemetic drugs for managing cisplatin-based HEC-induced nausea and vomiting in China. Improving the management of CINV is crucial, and these findings provide valuable insights into optimizing antiemetic drug practices.

Suppressing the Substance P-NK1R Signalling Protects Mice against Sepsis-Associated Acute Inflammatory Injury and Ferroptosis in the Liver and Lungs.

Substance P (SP), encoded by the TAC1/Tac1 gene, acts as a significant mediator in dysregulated systemic inflammatory response and associated organ injury in sepsis by activating the neurokinin-1 receptor (NK1R). This study investigated the impact of SP-NK1R signaling on ferroptosis in the liver and lungs of mice with sepsis. Sepsis was induced by caecal ligation puncture (CLP) surgery in mice. The SP-NK1R signaling was suppressed by Tac1 gene deletion, NK1R blockade, and a combination of these two approaches. The physiological conditions of mice were recorded. The profile of the SP-NK1R cascade, inflammatory response, ferroptosis, and tissue histology were investigated in the liver and lungs. Several manifestations of sepsis occurred in Tac1+/+ mice during the development of sepsis. Notably, hypothermia became significant four hours after the induction of sepsis. In the liver and lungs of mice subjected to CLP surgery, the concentrations of SP and NK1R were upregulated. Additionally, the concentrations of pro-inflammatory mediators, including cytokines (IL-1β, IL-6, and TNF-α) and chemokines (MCP-1 and MIP-2), were increased. Moreover, ferroptosis was elevated, as evidenced by increased concentrations of iron and MDA and reduced concentrations of GSH, Nrf2, and Gpx4. Suppressing the SP-NK1R cascade significantly mitigated CLP-surgery-induced alterations in mice. Importantly, these three approaches used to suppress SP-NK1R signaling showed similar effects on protecting mice against sepsis. In conclusion, increased SP-mediated acute inflammatory response and injury in the liver and lungs in mice with CLP-surgery-induced sepsis was associated with elevated ferroptosis. The detrimental effect of SP on sepsis was predominantly mediated by NK1R. Therefore, the suppression of increased SP-NK1R signaling and ferroptosis may be a promising adjuvant therapeutic candidate for sepsis and associated acute liver and lung injury.

Molecular mechanism of residual lumbago and leg pain after transforaminal endoscopic treatment of lumbar disc herniation

To observe the residual of lumbago and leg pain with contained type （CT） and non-contained type （NCT） lumbar disc herniation （LDH） after transforaminal endoscopic treatment, and to explore the role of hypoxia-inducible factor-1α（HIF-1α） and transient receptor potential vanillate 1（TRPV1） pathway. A total of 68 single-segment LDH patients were selected from July 2021 to October 2022, including 44 males and 24 females；aged 26 to 67 years old with an average of（43.63±11.94） years old；course of disease was 4 to 36 （18.91±10.34） months；body mass index was （24.45±4.00） kg·m-2；there were 7 cases of L3,4 segments, 32 cases of L4,5 segments, and 29 cases of L5S1 segments. All of them were performed with percutaneous intervertebral endoscopic extraction of nucleus pulposus and were divided into contained group（CT group） and non-contained group （NCT group） with 34 cases respectively according to the integrity of outer layer of fibrous annulus observed during operation. A total of 17 patients who underwent open surgery for scoliosis or vertebral fracture were selected as control group, including 12 males and 5 females；aged 21 to 65 years old with an average of （39.41±12.80） years old；body mass index was （24.86±4.11） kg·m-2. The relative mRNA expression quantity of HIF-1α, TRPV1 in nucleus pulposus were measured by quantitative real-time PCR. The contents of neurokinin 1 receptor （NK1R）, nerve growth factor （NGF）, vascular endothelial growth factor （VEGF） in nucleus pulposus and the serum substance P （SP） and calcitonin gene-related peptide （CGRP） were detected by enzyme linked immunosorbent assay （ELISA）. The threshold of lumbar tenderness was detected by a pressure pain meter. The degree of lumbago and lumbar function were evaluated by visual analog scale （VAS） and Oswestry disability index （ODI） separately. The residual rate of postoperative lumbago and leg pain was assessed. The mRNA relative expression quantity of HIF-1α and TRPV1, and the contents of NK1R, NGF and VEGF in nucleus pulposus, and the levels of serum SP and CGRP before surgery in the NCT group were higher than those in the CT group（P<0.05）, and those in the CT group were higher than the control group（P<0.05）. At day 7 after surgery, the serum SP and CGRP levels, lumbago and leg pain VAS scores and lumbar ODI index in two LDH groups were lower than before surgery （P<0.05）, and those in the NCT group were higher than the CT group（P<0.05）, and the threshold of lumbar tenderness in the NCT group was lower than the CT group（P<0.05）. The differences of lumbago and leg pain VAS scores, lumbar ODI index and lumbar tenderness threshold between preoperative and postoperative 7 days in the NCT group were lower than those in the CT group（P<0.05）. The residual rate of lumbago and leg pain at 7 days after surgery in the NCT group was higher than that in the CT group（P<0.05）. HIF-1α and TRPV1 pathway promoted the excessive production of NGF, VEGF, NK1R in nucleus pulposus and serum neuropeptides SP and CGRP, which may lead to the higher residual rate of lumbago and leg pain with non-contained lumbar disc herniation postoperative.

Adherence to antiemetic guidelines in solid cancer patients receiving highly emetogenic chemotherapy in Korea.

Highly emetogenic chemotherapy (HEC) is known to induce nausea and vomiting (CINV) in approximately 90% of cancer patients undergoing this regimen unless proper prophylactic antiemetics are administered. This study aimed to analyze the use of a three-drug prophylactic antiemetic regimen during the first cycle of chemotherapy and assess the compliance rate with the National Comprehensive Cancer Network (NCCN) guidelines. This retrospective study utilized data from the National Inpatient Sample database from 2016 to 2020 provided by the Health Insurance Review and Assessment Service. The claims data encompassed 10 to 13% of inpatients admitted at least once each year. Patients with solid cancers treated with two HEC regimens, namely anthracycline + cyclophosphamide (AC) and cisplatin-based regimens, were selected as the study population. We evaluated the use of a three-drug prophylactic antiemetic regimen, including a neurokinin-1 receptor antagonist, a 5-hydroxytryptamine-3 receptor antagonist, and dexamethasone and compliance with the NCCN guidelines. Multiple logistic regression was conducted to estimate the influence of variables on guideline adherence. A total of 3119 patients were included in the analysis. The overall compliance rate with the NCCN guidelines for prophylactic antiemetics was 74.3%, with higher rates observed in the AC group (87.9%) and lower rates in the cisplatin group (60.4%). The AC group had a 6.37 times higher likelihood of receiving guideline-adherent antiemetics than the cisplatin group. Further analysis revealed that, compared to 2016, the probability of complying with the guidelines in 2019 and 2020 was 0.72 times and 0.76 times lower, respectively. This study showed that a considerable proportion of HEC-treated patients received guideline-adherent antiemetic therapies. However, given the variations in adherence rates between different chemotherapy regimens (AC vs. cisplatin), efforts to improve adherence and optimize antiemetic treatment remain essential for providing the best possible care for patients experiencing CINV.

The combined anti-tumor effects of 5-fluorouracil and neurokinin receptor inhibitor, aprepitant, against colorectal cancer: In vitro and in vivo study.

Colorectal cancer (CRC) is one of the world's largest health concerns with growing global incidence and mortality. The potential value of the neurokinin-1 receptor as a therapeutic target has been reported in several tumor types, including CRC. Here we examined the potential anti-tumor effects of a clinically approved neurokinin-1 receptor antagonist, aprepitant, alone and its combination with 5-Fluorouracil (5-FU) as a first choice CRC chemotherapeutic drug, in both in vitro and in vivo models of CRC. MTT assay was employed for assessing cell proliferation. mRNA expression levels were determined by quantitative real-time PCR (qRT-PCR). Flow cytometric analysis of apoptosis was performed using an Annexin-V/propidium iodide assay kit. We finally conducted an in vivo experiment in a mouse model of CRC to confirm the in vitro antiproliferative activity of aprepitant and 5-FU. We found that aprepitant and 5-FU significantly reduced CRC cell viability. The combination of drugs exhibited potent synergistic growth inhibitory effects on CRC cells. Moreover, aprepitant and 5-FU induced apoptosis and altered the levels of apoptotic genes (up-regulation of Bax, and p53 along with downregulation of Bcl-2). Importantly, the aprepitant and 5-FU combination showed a more pronounced impact on apoptosis and associated genes than either of the agents alone. Furthermore, aprepitant reduced tumor growth in vivo and led to significantly longer survival time, and this effect was more prominent when using the aprepitant and 5-FU combination. Collectively, combinatory treatment with aprepitant and 5-FU potentially exerts synergistic growth inhibition and apoptosis induction in CRC, deserving further consideration as a novel strategy for CRC patients.

Excimer light effect on neurogenic inflammation in active versus stable psoriasis lesions

Neurogenic inflammation, mediated by T helper 17 cell (Th17) and neurons that release neuropeptides such as substance P (SP), is thought to play a role in the pathogenesis of psoriasis. Excimer light is used in the treatment of psoriasis via induction of T cell apoptosis. The objective of this study is to study the effect of excimer light on active versus stable psoriasis and investigate the levels of substance P and its receptor in both groups. The study included 27 stable and 27 active psoriatic patients as well as 10 matched healthy controls. Clinical examination (in the form of local psoriasis severity index (PSI) and visual analogue scale (VAS)) was done to determine disease severity, level of itching, and quality of life. Tissue levels of SP and neurokinin-1 receptor (NK-1R) were measured by ELISA before and after 9 excimer light sessions in 43 patients. A statistically significant lower levels of PSI and VAS were reached after therapy with no significant difference between the stable and active groups. The mean tissue levels of SP before therapy were significantly higher than the control group. Lower levels of SP and NK-1 receptor were found after treatment overall and in each group. Excimer therapy can be effective for both stable and active plaque psoriasis and this effect could be partly through its role on ameliorating the neurogenic inflammation.

Placental mRNA Expression of Neurokinin B Is Increased in PCOS Pregnancies with Female Offspring.

Current research suggests that polycystic ovary syndrome (PCOS) might originate in utero and implicates the placenta in its pathogenesis. Kisspeptin (KISS1) and neurokinin B (NKB) are produced by the placenta in high amounts, and they have been implicated in several pregnancy complications associated with placental dysfunction. However, their placental expression has not been studied in PCOS. We isolated mRNA after delivery from the placentae of 31 PCOS and 37 control women with term, uncomplicated, singleton pregnancies. The expression of KISS1, NKB, and neurokinin receptors 1, 2, and 3 was analyzed with real-time polymerase chain reaction, using β-actin as the reference gene. Maternal serum and umbilical cord levels of total testosterone, sex hormone-binding globulin (SHBG), free androgen index (FAI), androstenedione, dehydroepiandrosterone sulfate (DHEAS), Anti-Mullerian hormone (AMH), and estradiol were also assessed. NKB placental mRNA expression was higher in PCOS women versus controls in pregnancies with female offspring. NKB expression depended on fetal gender, being higher in pregnancies with male fetuses, regardless of PCOS. NKB was positively correlated with umbilical cord FAI and AMH, and KISS1 was positively correlated with cord testosterone and FAI; there was also a strong positive correlation between NKB and KISS1 expression. Women with PCOS had higher serum AMH and FAI and lower SHBG than controls. Our findings indicate that NKB might be involved in the PCOS-related placental dysfunction and warrant further investigation. Studies assessing the placental expression of NKB should take fetal gender into consideration.

Effect of Selective 5-Hydroxytryptamine-3 Receptor and Neurokinin-1 Receptor Antagonists on Hemodynamic Changes and Arrhythmogenic Potential in Patients Receiving Chemotherapy: A Retrospective, Observational Study

Background: Prior speculation suggests that selective 5-hydroxytryptamine-3 receptors and neurokinin-1 receptor antagonists may increase arrhythmia risk and induce electrocardiographic changes. This study examined the effect of anti-emetic medications on arrhythmogenic potential and hemodynamic alterations. Methods: We considered patients aged 18 or above receiving chemotherapy between June 2013 and December 2013. Patients were grouped by anti-emetic medication: intravenous granisetron (Group G), oral aprepitant plus IV granisetron (Group AG), IV palonosetron (Group P), and oral aprepitant plus IV palonosetron (Group AP). We recorded blood pressure and electrocardiography initially and at the thirtieth minute post-medication, focusing on P dispersion, QTc dispersion, and systolic/diastolic blood pressure alterations. Results: The study included 80 patients (20 per group). Baseline systolic/diastolic blood pressure and P dispersion showed no significant variance. However, the baseline QTc dispersion was significantly lower in Groups P and AP than G and AG. The thirtieth-minute systolic/diastolic blood pressures were significantly lower than the baseline for Groups AG and AP, and the heart rates decreased in all groups. Group P showed significantly fewer blood pressure changes. Conclusions: We found no arrhythmogenic potential linked to granisetron, palonosetron, and aprepitant. Hypotension was more frequent at 30 min post-medication in granisetron or aprepitant recipients. Considering no hypotension occurred when using palonosetron alone, this treatment was deemed safer.

Efficacy of aprepitant for refractory pruritus in patients with epidermolysis bullosa and atopic dermatitis: A retrospective study.

At a single-center pediatric hospital, the neurokinin-1 receptor antagonist aprepitant was used to treat refractory pruritus in epidermolysis bullosa (EB) and atopic dermatitis (AD). Thirty-seven patients were included (24 EB patients, 13 AD patients), ages 10 months to 37 years. 58% (14/24) of patients with EB and 85% (11/13) of patients with AD reported aprepitant was effective in decreasing their pruritus, with age-related differences in efficacy observed in EB patients, and access to the medication by insurance denial or availability of the drug as a barrier to use. Aprepitant shows promise in controlling refractory pruritus in pediatric EB and AD patients and deserves further study.

Investigation of the neurokinin receptor 1 structures and its regulation by its endogenous activator substance P and the antagonist aprepitant

Investigation of the neurokinin receptor 1 structures and its regulation by its endogenous activator substance P and the antagonist aprepitant

Semi-synthetic nanobody-ligand conjugates exhibit tunable signaling properties and enhanced transcriptional outputs at neurokinin receptor-1.

Antibodies have proven highly valuable for therapeutic development; however, they are typically poor candidates for applications that require activation of G protein-coupled receptors (GPCRs), the largest collection of targets for clinically approved drugs. Nanobodies (Nbs), the smallest antibody fragments retaining full antigen-binding capacity, have emerged as promising tools for pharmacologic applications, including GPCR modulation. Past work has shown that conjugation of Nbs with ligands can provide GPCR agonists that exhibit improved activity and selectivity compared to their parent ligands. The neurokinin-1 receptor (NK1R), a GPCR targeted for the treatment of pain, is activated by peptide agonists such as Substance P (SP) and neurokinin A (NKA), which induce signaling through multiple pathways (Gs , Gq and β-arrestin). In this study, we investigated whether conjugating NK1R ligands with Nbs that bind to a separate location on the receptor would provide chimeric compounds with distinctive signaling properties. We employed sortase A-mediated ligation to generate several conjugates consisting of Nbs linked to NK1R ligands. Many of these conjugates exhibited divergent and unexpected signaling properties and transcriptional outputs. For example, some Nb-NKA conjugates showed enhanced receptor binding capacity, high potency partial agonism, prolonged cAMP production, and an increase in transcriptional output associated with Gs signaling; whereas other conjugates were virtually inactive. Nanobody conjugation caused only minor alterations in ligand-induced upstream Gq signaling with unexpected enhancements in transcriptional (downstream) responses. Our findings underscore the potential of nanobody conjugation for providing compounds with advantageous properties such as biased agonism, prolonged duration of action, and enhanced transcriptional responses. These compounds hold promise not only for facilitating fundamental research on GPCR signal transduction mechanisms but also for the development of more potent and enduring therapeutics.

Management of nausea and vomiting (N/V) following first-line (1L) zolbetuximab + chemotherapy treatment in claudin-18.2 (CLDN18.2)+, HER2−, locally advanced (LA) unresectable or metastatic gastric or gastroesophageal junction (mG/GEJ) adenocarcinoma: Analysis from the phase 3 SPOTLIGHT and GLOW studies.

372 Background: The phase 3 SPOTLIGHT (NCT03504397) and GLOW (NCT03653507) studies showed clinically meaningful, statistically significant improvement in PFS and OS using 1L zolbetuximab + chemotherapy vs placebo (PBO) + chemotherapy in patients (pts) with CLDN18.2+, HER2−, LA unresectable or mG/GEJ adenocarcinoma. N/V were the most common treatment-emergent adverse events (TEAEs) reported in the zolbetuximab arm of these studies. We report an analysis of the incidence and management of N/V in SPOTLIGHT and GLOW. Methods: In SPOTLIGHT, pts (N = 565) were randomized 1:1 to zolbetuximab + mFOLFOX6 vs PBO + mFOLFOX6. In GLOW, pts (N = 507) were randomized 1:1 to zolbetuximab + CAPOX vs PBO + CAPOX. In both studies, neurokinin-1 receptor blockers (NK-1), selective serotonin receptor blockers (5-HT3), and other prophylactic antiemetic regimens were recommended to prevent and mitigate N/V per institutional care and guidelines. Results: A total of 279 pts in SPOTLIGHT and 253 pts in GLOW received zolbetuximab + chemotherapy. In SPOTLIGHT and GLOW combined, nausea occurred in 58% vs 18% of pts, and vomiting occurred in 43% vs 15% of pts in the first vs second zolbetuximab infusions, respectively; lower incidences of N/V were observed thereafter. During the first zolbetuximab infusion, the first episode of N/V occurred within 1 hour (median time, 48.0 min in SPOTLIGHT and 56.5 min in GLOW). Antiemetic usage and associated N/V rates are presented in the Table. The 96 pts in SPOTLIGHT and 52 pts in GLOW who had infusion modifications in cycle 1 due to TEAEs had numerically higher infusion rates than pts without infusion modifications; 85% of these modifications in SPOTLIGHT and 79% in GLOW were due to N/V. Zolbetuximab was discontinued within the first 9 weeks in 11 and 7 pts in SPOTLIGHT and 6 and 4 pts in GLOW due to nausea or vomiting, respectively. Conclusions: In SPOTLIGHT and GLOW, slower infusion rate and use of antiemetic combinations may have helped to mitigate N/V. These strategies will be important to support continued treatment and allow pts to achieve maximum clinical benefit with zolbetuximab + chemotherapy. Clinical trial information: NCT03504397 and NCT03653507 . [Table: see text]

Antagonists of somatostatin and NK1 receptors synergistically induce catalepsy in middle-aged Wistar rats

Objectives: A decrease in levels of somatostatin (SST) and substance P (SP) is observed in the parkinsonian brain. Previously, brain SST deficit in rats simulated by i.c.v. injections of SST receptor antagonist, cyclosomatostatin (cSST), was found to promote the development of catalepsy. The role of SP, a natural ligand of neurokinin-1 (NK1) receptors, in the development of catalepsy is currently unclear. Here, we evaluated whether simultaneous blockade of central somatostatin and NK1 receptors is able to initiate catalepsy and affect dopamine turnover in the nigrostriatal area of the brain.\nMaterials and methods: The experiments were carried out on middle-aged Wistar rats. The blockade of somatostatin and NK1 receptors was simulated by intracerebroventricular injections of cSST and substance L-733,060, respectively. Catalepsy was evaluated by the bar test. The levels of dopamine and its metabolites in the dorsal striatum and substantia nigra were measured by using HPLC.\nResults: No catalepsy was induced by cSST at 1.0 µg and L-733,060 at 10.0 ng injected separately. However, co-administration of these agents initiated catalepsy and influenced dopamine metabolism in the nigrostriatal area. Cataleptogenic action of the combination was reversed by SP. \nConclusion: The present findings testify that there is some sort of synergy between cSST and L-733,060 in initiation of catalepsy. In the light of these data, PD-related simultaneous brain deficit in SST and SP might be relevant for pathogenesis of extrapyramidal dysfunctions. Given the presented results, the processes mediated by central SST and NK1 receptors may be potential therapeutic targets for parkinsonism.

The analgesic effects of botulinum neurotoxin by modulating pain-related receptors; A literature review.

Botulinum neurotoxins (BoNTs), produced by Clostridium botulinum, have been used for the treatment of various central and peripheral neurological conditions. Recent studies have suggested that BoNTs may also have a beneficial effect on pain conditions. It has been hypothesized that one of the mechanisms underlying BoNTs' analgesic effects is the inhibition of pain-related receptors' transmission to the neuronal cell membrane. BoNT application disrupts the integration of synaptic vesicles with the cellular membrane, which is responsible for transporting various receptors, including pain receptors such as TRP channels, calcium channels, sodium channels, purinergic receptors, neurokinin-1 receptors, and glutamate receptors. BoNT also modulates the opioidergic system and the GABAergic system, both of which are involved in the pain process. Understanding the cellular and molecular mechanisms underlying these effects can provide valuable insights for the development of novel therapeutic approaches for pain management. This review aims to summarize the experimental evidence of the analgesic functions of BoNTs and discuss the cellular and molecular mechanisms by which they can act on pain conditions by inhibiting the transmission of pain-related receptors.

Neuropeptide substance P attenuates colitis by suppressing inflammation and ferroptosis via the cGAS-STING signaling pathway.

Neuropeptide substance P (SP) belongs to a family of bioactive peptides and regulates many human diseases. This study aims to investigate the role and underlying mechanisms of SP in colitis. Here, activated SP-positive neurons and increased SP expression were observed in dextran sodium sulfate (DSS)-induced colitis lesions in mice. Administration of exogenous SP efficiently ameliorated the clinical symptoms, impaired intestinal barrier function, and inflammatory response. Mechanistically, SP protected mitochondria from damage caused by DSS or TNF-α exposure, preventing mitochondrial DNA (mtDNA) leakage into the cytoplasm, thereby inhibiting the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. SP can also directly prevent STING phosphorylation through the neurokinin-1 receptor (NK1R), thereby inhibiting the activation of the TBK1-IRF3 signaling pathway. Further studies revealed that SP alleviated the DSS or TNF-α-induced ferroptosis process, which was associated with repressing the cGAS-STING signaling pathway. Notably, we identified that the NK1R inhibition reversed the effects of SP on inflammation and ferroptosis via the cGAS-STING pathway. Collectively, we unveil that SP attenuates inflammation and ferroptosis via suppressing the mtDNA-cGAS-STING or directly acting on the STING pathway, contributing to improving colitis in an NK1R-dependent manner. These findings provide a novel mechanism of SP regulating ulcerative colitis (UC) disease.

The Efficacy of Tradipitant in Patients With Diabetic and Idiopathic Gastroparesis in a Phase 3 Randomized Placebo-Controlled Clinical Trial

Neurokinin receptor 1 (NK1R) antagonists are effective in reducing nausea and vomiting in chemo-therapy induced emesis. We investigated the safety and efficacy of tradipitant, an NK1R antagonist, in patients with idiopathic and diabetic gastroparesis. 201 adults with gastroparesis were randomly assigned to oral tradipitant 85 mg (n = 102) or placebo (n = 99) twice daily for 12 weeks. Symptoms were assessed by a daily symptom dairy, Gastroparesis Cardinal Symptom Index scores, and other patient-reported questionnaires. Blood levels were monitored for an exposure-response analysis. The primary outcome was change from baseline to week 12 in average nausea severity, measured by daily symptom diary. The ITT population did not meet the pre-specified primary endpoint at Week 12 (difference in nausea severity change drug vs. placebo, P = .741) or pre-specified secondary endpoints. Post hoc analyses were performed to control for drug exposure, rescue medications, and baseline severity inflation. Subjects with high blood levels of tradipitant significantly improved average nausea severity beginning at early time points Weeks 2 through Week 4. In post hoc sensitivity analyses, tradipitant treatment demonstrated strengthened effects, with statistically significant improvements in nausea at Week 12. Although tradipitant did not reach significance in the ITT population, a pharmacokinetic exposure-response analysis demonstrated significant effects with adequate tradipitant exposure. When accounting for confounding factors such as baseline severity inflation and rescue medication, a statistically significant effect was also observed. These findings suggest that tradipitant has potential as a treatment for the symptom of nausea in gastroparesis. [ClincialTrials.gov number, NCT04028492].