Substance P (SP), encoded by the Tac1 gene, has been shown to promote leukocyte infiltration and organ impairment in mice with sepsis. Neurokinin-1 receptor (NK1R) is the major receptor that mediates the detrimental impact of SP on sepsis. This investigation studied whether SP affects the expression of adhesion molecules, including intercellular cell adhesion molecule-1 (ICAM1) and vascular cell adhesion molecule-1 (VCAM1) on vascular endothelial cells in the liver and lungs, contributing to leukocyte infiltration in these tissues of mice with sepsis. Sepsis was induced by caecal ligation and puncture (CLP) surgery in mice. The actions of SP were inhibited by deleting the Tac1 gene, blocking NK1R, or combining these two methods. The activity of myeloperoxidase and the concentrations of ICAM1 and VCAM1 in the liver and lungs, as well as the expression of ICAM1 and VCAM1 on vascular endothelial cells in these tissues, were measured. The activity of myeloperoxidase and the concentration of ICAM1 and VCAM1 in the liver and lungs, as well as the expression of ICAM1 and VCAM1 on vascular endothelial cells in these tissues, increased in mice with CLP surgery-induced sepsis. Suppressing the biosynthesis of SP and its interactions with NK1R attenuated CLP surgery-induced alterations in the liver and lungs of mice. Our findings indicate that SP upregulates the expression of ICAM1 and VCAM1 on vascular endothelial cells in the liver and lungs, thereby increasing leukocyte infiltration in these tissues of mice with CLP surgery-induced sepsis by activating NK1R.

Substance P (SP) is a neuropeptide expressed by nerves and an array of cells that serves as a critical mediator of neuroinflammation. Our recent work has demonstrated that blocking the preferred receptor for SP, neurokinin-1 receptor (NK1R), effectively suppresses the induction of acute dry eye disease (DED) by preserving regulatory T cell (Treg) function, while inhibiting antigen-presenting cell (APC) maturation and subsequent generation of effector Th17 cells (eTh17). Clinically, DED is a chronic disorder characterized by sustained ocular surface inflammation which is mediated by long-lived memory Th17 cells (mTh17) demonstrated in our well-established chronic DED model. The present study aimed to further understand the function of SP in the chronic phase of DED and its role in regulating the underlying pathogenic mTh17. In vitro culture of effector T cells isolated from acute DED with SP led to an enhanced conversion of eTh17 to mTh17, while culturing memory T cells isolated from chronic DED with SP effectively preserved the mTh17 cells. In contrast, the addition of an NK1R antagonist in the cultures abolished the SP-mediated effects. Furthermore, in vivo treatment with the NK1R antagonist during the resolution phase of acute DED significantly suppressed mTh17 generation, and treatment in the chronic phase of DED disrupted the maintenance of mTh17. Taken together, our results demonstrate that increased expression of SP promotes mTh17 generation and maintenance in chronic DED, and thus blockade of SP represents a novel promising mTh17-targeting strategy in treating chronic ocular surface inflammation.

Purpose: To evaluate the therapeutic efficacy of topical application of a neurokinin-1 receptor (NK1R) antagonist in a rabbit model of nonallergic ocular redness. Methods: Nonallergic ocular redness was induced in rabbits by a single, topical application of dapiparzole hydrochloride eye drops (0.5%, 1%, 2%, or 5%). The NK1R antagonist L-703,606 was topically applied to the eye at the same time of induction or 20 min after induction, and phosphate buffered saline (PBS) treatment served as the control. Superior bulbar conjunctival images were taken every 30 s for the first 2 min, followed by every 4 min for 8 min, and then every 10 min until 1 h. The severity of ocular redness was evaluated on the images using ImageJ-based ocular redness index (ORI) calculations. Results: The ORI scores were significantly increased after the application of 0.5%, 1%, 2%, or 5% dapiparzole at each time point evaluated, with the most severe redness induced by the 5% dapiprazole that led to a maximal mean increase in ORI score of 14 at 20 min post-induction and thus used for subsequent evaluation of therapeutic efficacy of NK1R antagonism. Topical L-703,606, when applied at the same time as dapiprazole induction, significantly suppressed the increase of ORI scores at all time points (∼40% decrease). Furthermore, when applied at 20 min after dapiprazole induction, L-703,606 rapidly and effectively suppressed the increase of ORI scores at 30, 40, 50, and 60 min (∼30% decrease). Conclusions: Topical blockade of NK1R effectively prevents and alleviates nonallergic ocular redness in a novel animal model.

µ-Opioid receptors (MORs) are responsible for mediating both the analgesic and respiratory effects of opioid drugs. By binding to MORs in brainstem regions involved in controlling breathing, opioids produce respiratory depressive effects characterized by slow and shallow breathing, with potential cardiorespiratory arrest and death during overdose. To better understand the mechanisms underlying opioid-induced respiratory depression, thorough knowledge of the regions and cellular subpopulations that may be vulnerable to modulation by opioid drugs is needed. Using in situ hybridization, we determined the distribution and coexpression of Oprm1 (gene encoding MORs) mRNA with glutamatergic (Vglut2) and neurokinin-1 receptor (Tacr1) mRNA in medullary and pontine regions involved in breathing control and modulation. We found that >50% of cells expressed Oprm1 mRNA in the preBötzinger complex (preBötC), nucleus tractus solitarius (NTS), nucleus ambiguus (NA), postinspiratory complex (PiCo), locus coeruleus (LC), Kölliker-Fuse nucleus (KF), and the lateral and medial parabrachial nuclei (LBPN and MPBN, respectively). Among Tacr1 mRNA-expressing cells, >50% coexpressed Oprm1 mRNA in the preBötC, NTS, NA, Bötzinger complex (BötC), PiCo, LC, raphe magnus nucleus, KF, LPBN, and MPBN, whereas among Vglut2 mRNA-expressing cells, >50% coexpressed Oprm1 mRNA in the preBötC, NTS, NA, BötC, PiCo, LC, KF, LPBN, and MPBN. Taken together, our study provides a comprehensive map of the distribution and coexpression of Oprm1, Tacr1, and Vglut2 mRNA in brainstem regions that control and modulate breathing and identifies Tacr1 and Vglut2 mRNA-expressing cells as subpopulations with potential vulnerability to modulation by opioid drugs.NEW & NOTEWORTHY Opioid drugs can cause serious respiratory side-effects by binding to µ-opioid receptors (MORs) in brainstem regions that control breathing. To better understand the regions and their cellular subpopulations that may be vulnerable to modulation by opioids, we provide a comprehensive map of Oprm1 (gene encoding MORs) mRNA expression throughout brainstem regions that control and modulate breathing. Notably, we identify glutamatergic and neurokinin-1 receptor-expressing cells as potentially vulnerable to modulation by opioid drugs and worthy of further investigation using targeted approaches.

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.

Triple-negative breast cancer (TNBC) lacks the expression of oestrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), rendering it unresponsive to endocrine therapy and HER2 targeted treatments. Though certain chemotherapeutics targeting the cell cycle have shown efficacy to a certain extent, the presence of chemotherapy-resistant cancer stem cells (CSCs) presents a significant challenge in tackling TNBC. Multiple lines of evidence suggest the upregulation of neuropeptide Substance P (SP), its NK-1 receptor (NK1R) and the Cyclooxygenase-2 (COX-2) enzyme in TNBC patients. Upregulation of the SP/NK1R system and COX-2 influences major signalling pathways involved in cell proliferation, growth, survival, angiogenesis, inflammation, metastasis and stem cell activity. The simultaneous activation and crosstalk between the pathways activated by SP/NK1R and COX-2 consequently increase the levels of key regulators of self-renewal pathways in CSCs, promoting stemness. The combination therapy with NK1R antagonists and COX-2 inhibitors can simultaneously target TNBC cells and CSCs, thereby enhancing treatment efficacy and reducing the risk of recurrence and relapse. This review discusses the rationale for combining NK1R antagonists and COX-2 inhibitors for the better management of TNBC and a novel strategy to deliver drug cargo precisely to the tumour site to address the challenges associated with off-target binding.

UNASSIGNED: At present, acupuncture-related practices have been widely used to treat psoriasis. In our study, we investigated the effect and explored the mechanism of electroacupuncture (EA) on acupoints Baihui (DU20) and Xuehai (SP10) for the treatment of psoriasis.
UNASSIGNED: Imiquimod-induced psoriasis-like mouse model was used in this study. Mice were treated with electroacupuncture at DU20 and SP10 (depth of 2-3 mm, frequency of 2/15 Hz, intensity of 0.5-1.0 mA, 10 min/day). The severity of psoriasis-like lesions for each group was assessed. In addition, histological analysis of the lesions were performed. The levels of inflammatory cytokines were determined using Elisa. The expression levels of Substance P (SP) and NK1R were measured using Western blotting. In addition, NK1R inhibitor was administrated to evaluate the target of electroacupuncture in our mouse model.
UNASSIGNED: Electroacupuncture significantly alleviated IMQ-induced skin lesions and epidermal thickness, accompanied with reduced keratinocyte proliferation, CD3+, CD4+, and CD8+ T cells infiltration. The reduced levels of inflammatory cytokines was observed after electroacupuncture treatment. In addition, electroacupuncture inhibited the expression levels of SP and NK1R. NK1R inhibitor could ameliorate lesional symptoms and suppress epidermal thickening and CD3+, CD4+, and CD8 + T cell infiltration.
UNASSIGNED: Electroacupuncture relieved psoriasis-like inflammation and T cell infiltration. This therapeutic action was likely mediated by the modulation of Substance P and its receptor NK1R.

Different studies have highlighted the role of Substance P / Neurokinin 1 Receptor (SP/NK-1R) axis in multiple hallmarks of cancer including cell transformation, proliferation, and migration as well as angiogenesis and metastasis of a wide range of solid tumors including colorectal cancer. Until now, the selective high-affinity antagonist of human SP/NK1-R aprepitant (Emend) has been authorized by the Food and Drug Administration as a low dosage medication to manage and treat chemotherapy-induced nausea. However, increasing evidence in recent years support the potential utility of high doses of aprepitant as an antitumor agent and thus, opening the possibility to the pharmacological repositioning of SP/NK1-R antagonists as an adjuvant therapy to conventional cancer treatments. In this review, we summarize current knowledge on the molecular basis of colorectal cancer as well as the pathophysiological importance of SP/NK1-R and the potential utility of SP/NK-1R axis as a therapeutic target in this malignancy.

BACKGROUND: Numerous biochemical reactions leading to altered cell proliferation cause tumorigenesis and cancer treatment resistance. The mechanisms implicated include genetic and epigenetic changes, modified intracellular signaling, and failure of control mechanisms caused by intrinsic and extrinsic factors alone or combined. No unique biochemical events are responsible; entangled molecular reactions conduct the resident cells in a tissue to display uncontrolled growth and abnormal migration. Copious experimental research supports the etiological responsibility of NK-1R (neurokinin-1 receptor) activation, alone or cooperating with other mechanisms, in cancer appearance in different tissues. Consequently, a profound study of this receptor system in the context of malignant processes is essential to design new treatments targeting NK-1R-deviated activity.
METHODS: This study reviews and discusses recent literature that analyzes the main signaling pathways influenced by the activation of neurokinin 1 full and truncated receptor variants. Also, the involvement of NK-1R in cancer development is discussed.
CONCLUSIONS: NK-1R can signal through numerous pathways and cross-talk with other receptor systems. The participation of override or malfunctioning NK-1R in malignant processes needs a more precise definition in different types of cancers to apply satisfactory and effective treatments. A long way has already been traveled: the current disposal of selective and effective NK-1R antagonists and the capacity to develop new drugs with biased agonistic properties based on the receptor\'s structural states with functional significance opens immediate research action and clinical application.

BACKGROUND: Neurokinin-1 receptor (NK-1R) and normal T cell expressed and secreted (RANTES) have been shown to play important roles in allergic rhinitis (AR). However, whether the regulating effect of NK-1R in AR is achieved via RANTES remains unknown.
METHODS: In the present study, Sprague-Dawley rats were sensitized and challenged with ovalbumin to make AR models. During the challenge period, the rats were treated intranasally with NK-1R-specific small interfering RNA (siRNA) for NKR group, negative siRNA for NCS group, rats in NSAR group and NS group were given saline. The amount of nasal secretion and the numbers of nose rubs and sneezes were measured in each rat. The levels of NK-1R and RANTES in the nasal mucosal tissues were determined through real-time fluorescence quantitative RT-PCR and immunohistochemical staining. The numbers of eosinophils in the collected nasal lavage fluid (NLF) were counted, and the concentration of RANTES in NLF was determined by enzyme-linked immunosorbent assay.
RESULTS: Compared with that in the NS group, the expression of NK-1R and RANTES was significantly higher in the nasal mucosa of NSAR and NCS group rats. The sneezing and nose rubbing counts and the amount of nasal secretions were increased significantly in the NSAR and NCS groups. Rats in the NKR group experienced greater relief from AR symptoms than rats in the NSAR and NCS groups. Furthermore, knockdown of NK-1R expression also significantly eliminated RANTES expression and eosinophil infiltration in the nasal mucosa of NKR group rats.
CONCLUSIONS: For the first time, we show that intranasal treatment with NK-1R-specific siRNA can significantly decrease RANTES expression, AR-related symptoms, and eosinophil inflammation, suggesting that the regulating effect of NK-1R in the development of AR occurs via alteration of RANTES expression.