Scaffold-based synergistic enhancement of stem cell effects for therapeutic angiogenesis in critical limb ischemia: an experimental animal study.

Purpose: Stem cell-based therapies are considered an alternative approach for critical limb ischemia (CLI) patients with limited or exhausted options, yet their clinical use is limited by the lack of sustainability and unclear mechanism of action. In this study, a substance P-conjugated scaffold was injected with mesenchymal stem cells (MSCs) into an animal model of CLI to verify whether angiogenesis could be enhanced. Methods: A self-assembling peptide (SAP) was conjugated with substance P, known to have the ability to recruit host stem cells into the site of action. This SAP was injected with MSCs into ischemic hindlimbs of rats, and the presence of MSCs was verified by immunohistochemical (IHC) staining of MSC-specific markers at days 7, 14, and 28. The degree of angiogenesis, cell apoptosis, and fibrosis was also quantified. Results: Substance P-conjugated SAP was able to recruit intrinsic MSCs into the ischemic site of action. When injected in combination with MSCs, the presence of both injected and recruited MSCs was found in the ischemic tissues by double IHC staining. This in turn led to a higher degree of angiogenesis, less cell apoptosis, and less tissue fibrosis compared to the other groups at all time points. Conclusion: The combination of substance P-conjugated SAP and MSCs was able to enhance angiogenesis and tissue repair, which was achieved by the additive effect from exogenously administered and intrinsically recruited MSCs. This scaffold-based intrinsic recruitment approach could be a viable option to enhance the therapeutic effects in patients with CLI.

Substance P receptor signaling contributes to host maladaptive responses during enteric bacterial infection.

Immune responses in the intestine are intricately balanced to prevent pathogen entry without inducing immunopathology. The nervous system is well-established to interface with the immune system to fine-tune immunity in various organ systems including the gastrointestinal tract. Specialized sensory neurons can detect bacteria, bacterial products, and the resulting inflammation, to coordinate the immune response in the gastrointestinal tract. These sensory neurons release peptide neurotransmitters such as Substance P (SP), to induce both neuronal signaling and localized responses in non-neuronal cells. With this in mind, we assessed the immunoregulatory roles of SP receptor signaling during enteric bacterial infection with the non-invasive pathogen Citrobacter rodentium. Pharmacological antagonism of the SP receptor significantly reduced bacterial burden and prevented colonic crypt hyperplasia. Mice with SP receptor signaling blockade had significantly reduced inflammation and recruitment of T-cells in the colon. Reduced colonic T-cell recruitment is due to reduced expression of adhesion molecules on colonic endothelial cells in SP receptor antagonist-treated mice. Using SP receptor T-cell conditional knockout mice, we further confirmed SP receptor signaling enhanced select aspects of T-cell responses. Our data demonstrates that SP receptor signaling can significantly reduce inflammation and prevent host-maladaptive responses without impinging upon host protection.

The Utilization of Topical Insulin for Ocular Surface Diseases: A Narrative Review.

Various etiologies, including diabetic keratopathy (DK), dry eye disease (DED), and neurotrophic keratopathy (NK), can disrupt corneal homeostasis, exacerbating corneal epithelial defects. Topical insulin has emerged as a promising therapy for promoting corneal wound healing and addressing underlying pathologies. This review systematically evaluates the efficacy of topical insulin across different corneal disorders. A literature review was conducted across the PubMed, Google Scholar, and Scopus research databases. The search resulted in a total of 19 articles, consisting of clinical trials, retrospective studies, and case reports. In DK, topical insulin accelerates corneal wound healing post-vitreoretinal surgery with lower concentrations showing higher outcomes when compared to conventional therapy, possibly due to improved epithelial stem cell migration. In comparison, the dry-eye disease results are inconclusive regarding patient-reported outcomes and corneal staining. For NK, topical insulin accelerates corneal wound healing and restores corneal nerve sensation. Other persistent epithelial defect (PED) etiologies that have been treated with topical insulin are infection, immune-mediated, mechanical and chemical trauma, and chronic ocular surface alterations. Although individual mechanisms for the benefits of topical insulin for each of these etiologies have not been studied, the literature demonstrates that topical insulin is efficacious for PEDs regardless of etiology. Future clinical trials need to be conducted to further evaluate optimal dosing, duration, and use of topical insulin for the restoration of the corneal surface.

Analyzing Substance Levels and Pain Perception in Painless Labor: The Impact of Spinal Epidural Analgesia.

BACKGROUND: Inflammation affects labor by influencing contractions and dilation. Pain, often linked to tissue ischemia, involves mediators like nitric oxide (NO), TNF-α, and substance P (SP). Neuraxial analgesia, including combined spinal epidural analgesia (SEA) with levobupivacaine, is preferred for its effectiveness and minimal side effects in painless labor. Understanding the impact of painless labor techniques on biomolecular processes such as NO, TNF-α, and substance P levels is crucial for improving pain management strategies. This study investigates these effects in parturients undergoing SEA with levobupivacaine, contributing to the development of novel pain medications and enhancing obstetric care. METHODS: This experimental study, conducted at a General Hospital in Indonesia, involved 60 expectant mothers in labor or in the third trimester, expected to give birth vaginally at Permata Hati Metro Hospital. Blood serum was used for analysis, and serum NO, TNF-α, and SP levels were assessed using ELISA kit. RESULTS: There's a significant decrease in NO levels before and post-treatment in the SEA group compared to the control group (p < 0.05). However, no significant difference in TNF-α levels was observed between groups before and after treatment (p > 0.05). Additionally, there was no significant difference in SP levels between groups before treatment, but a significant difference was seen after treatment (p < 0.05). SEA significantly reduced labor pain compared to the control group (P < 0.05), with notable improvements in vital signs and APGAR scores, while also shortening labor duration (P < 0.001). CONCLUSION: In conclusion, SEA with levobupivacaine during painless labor reduces NO levels significantly and shows a trend of decreasing TNF-α and substance P levels, although not statistically significant, with clinical benefits for both patients and babies.

Examination of the Effect of Dimethyl Trisulfide in Acute Stress Mouse Model with the Potential Involvement of the TRPA1 Ion Channel.

Polysulfides are endogenously produced in mammals and generally associated with protective functions. Our aim was to investigate the effect of dimethyl trisulfide (DMTS) in a mouse model of acute stress. DMTS activates transient receptor potential ankyrin 1 (TRPA1) channels and leads to neuropeptide release, potentially that of substance P (SP). We hypothesize that DMTS might inhibit the degrading enzymes of endocannabinoids, so this system was also investigated as another possible pathway for mediating the effects of DMTS. Trpa1 gene wild-type (WT) and knockout (KO) mice were used to confirm the role of the TRPA1 ion channel in mediating the effects of DMTS. C57BL/6J, NK1 gene KO, and Tac1 gene KO mice were used to evaluate the effect of DMTS on the release and expression of SP. Some C57BL/6J animals were treated with AM251, an inhibitor of the cannabinoid CB1 receptor, to elucidate the role of the endocannabinoid system in these processes. Open field test (OFT) and forced swim test (FST) were performed in each mouse strain. A tail suspension test (TST) was performed in Trpa1 WT and KO animals. C-FOS immunohistochemistry was carried out on Trpa1 WT and KO animals. The DMTS treatment increased the number of highly active periods and decreased immobility time in the FST in WT animals, but had no effect on the Trpa1 KO mice. The DMTS administration induced neuronal activation in the Trpa1 WT mice in the stress-related brain areas, such as the locus coeruleus, dorsal raphe nucleus, lateral septum, paraventricular nucleus of the thalamus, and paraventricular nucleus of the hypothalamus. DMTS may have a potential role in the regulation of stress-related processes, and the TRPA1 ion channel may also be involved in mediating the effects of DMTS. DMTS can be an ideal candidate for further study as a potential remedy for stress-related disorders.

Stimulation of the calcium-sensing receptor induces relaxations through CGRP and NK1 receptor-mediated pathways in male rat mesenteric arteries.

Stimulation of the calcium-sensing receptor (CaSR) regulates vascular contractility, but cellular mechanisms involved remain unclear. This study investigated the role of perivascular sensory nerves in CaSR-induced relaxations of male rat mesenteric arteries. In fluorescence studies, colocalisation between synaptophysin, a synaptic vesicle marker, and the CaSR was present in the adventitial layer of arterial segments. Using wire myography, increasing external Ca2+ concentration ([Ca2+]o) from 1 to 10 mM induced vasorelaxations, previously shown to involve the CaSR, which were inhibited by pretreatment with capsaicin. [Ca2+]o-induced vasorelaxations were partially reduced by the calcitonin gene-related peptide (CGRP) receptor blockers, CGRP 8-37 and BIBN 4096, and the neurokinin 1 (NK1) receptor blocker L733,060. The inhibitory effect of CGRP 8-37 required a functional endothelium whereas the inhibitory action of L733,060 did not. Complete inhibition of [Ca2+]o-induced vasorelaxations occurred when CGRP 8-37 and L733,060 were applied together. [Ca2+]o-induced vasorelaxations in the presence of capsaicin were abolished by the ATP-dependent K+ channel (KATP) blocker PNU 37883, but unaffected by the endothelium nitric oxide synthase (eNOS) inhibitor L-NAME. We suggest that the CaSR on perivascular sensory nerves mediate relaxations in rat mesenteric arteries via endothelium-dependent and -independent mechanisms involving CGRP and NK1 receptor-activated NO production and KATP channels, respectively.

[Clinical effect of the warm acupuncture of Mongolian medicine on insomnia in the elderly and its brain-gut peptide mechanism: a randomized controlled trial].

OBJECTIVE: To observe the clinical effect and safety of the warm acupuncture of Mongolian medicine in treatment of insomnia in the elderly, and to explore its underlying brain-gut peptide mechanism. METHODS: Sixty elderly patients with insomnia were randomly divided into a warm acupuncture group and a western medication group, 30 cases in each group. In the warm acupuncture group, the warm acupuncture of Mongolian medicine was operated at Dinghuixue (at the center of the vertex, the crossing site of the anterior midline and the line connected the upper edges of two ear apexes), Heyixue (at the depression of the spinous process of the 7th cervical vertebra) or Xinxue (at the depression of the spinous process of the 6th thoracic vertebra) in each treatment. Only one of the above points was selected and stimulated for 20 min one treatment and the three points were used alternatively. The treatment was given once every day or every other day, 3 times a week, and for a total of 3 weeks. In the western medication group, estazolam tablets were administered orally, once a day, 1 mg before bedtime, consecutively for 3 weeks. Before and after treatment, as well as in 1-month follow-up visit after the treatment completion, the scores of the Pittsburgh sleep quality index (PSQI) and the insomnia severity index (ISI) were observed in the two groups. The serum brain-related peptide markers (substance P [SP], neuropeptide Y [NPY], 5-hydroxytryptamine 1A [5-HT1A] and 5-hydroxytryptamine 2A [5-HT2A]) were measured before and after treatment, and the clinical efficacy and safety was evaluated in the two groups. RESULTS: After treatment and in follow-up, the scores of sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disturbance and daytime dysfunction, as well as the total scores of PSQI, and ISI scores were all reduced in the two groups (P<0.05, P<0.01); and the scores in the warm acupuncture group were lower than those of the western medication group (P<0.05, P<0.01). After treatment, the levels of serum SP and 5-HT2A were decreased (P<0.01) and the levels of serum NPY and 5-HT1A were increased (P<0.01) when compared with those before treatment in the two groups. The levels of serum SP and 5-HT2A in the warm acupuncture group were lower than those of the western medication group (P<0.05), and the levels of serum NPY and 5-HT1A were higher than those of the western medication group (P<0.05). After treatment, the total effective rate was 93.3% (28/30) in the warm acupuncture group, which was higher than 83.3% (25/30) of the western medication group (P<0.05). No serious adverse reactions were found in the two groups. CONCLUSION: Warm acupuncture of Mongolian medicine can effectively improve the sleep quality of the elderly patients with insomnia, and its mechanism may be related to the regulation of the levels of serum SP, NPY, 5-HT1A and 5-HT2A.

Unveiling the Promising Role of Substance P/Neurokinin 1 Receptor in Cancer Cell Proliferation and Cell Cycle Regulation in Human Malignancies.

Neurokinin receptors are a family of G protein-coupled receptors that were first identified in the central and peripheral nervous systems. However these receptors were later found in other types of cells, therefore, new perspectives concerning their novel roles were described. Mammalian has three neurokinin receptors, among which neurokinin-1 receptors [NK1R] have been indicated to be involved in most, if not all, intracellular functions, primarily the regulation of cell proliferation. By interacting with its potent agonist, substance P [SP], NK1R can engage a variety of signaling pathways and serve as a platform for cells to proliferate by regulating the expression of the cell cycle-related genes. Furthermore, the activity of SP/NK1R is stimulated by various oncogenes, indicating the involvement of this pathway in human cancers. As a result, numerous NK1R antagonists have been investigated in oncology trials, and the promising anti-- cancer effect of these receptors has opened up new possibilities for incorporating these antagonists into cancer treatment. Considering these factors, gaining a deeper understanding of the SP/NK1R pathway could offer significant advantages for cancer patients. The more knowledge we acquire about this pathway, the greater the potential for exploiting it in the development of effective treatment strategies. Here, we present a comprehensive review of the current knowledge pertaining to the biological function of the SP/NK1R, with a specific emphasis on its recently discovered role in the regulation of cell proliferation. Moreover, we provide insights into the impact of this pathway in human cancers, along with an overview of the most significant NK1R antagonists currently utilized in cancer research studies.

Neurokinin-1 Receptor Antagonism Reduces Nonallergic Ocular Redness in a Rabbit Model.

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.

Substance P's Impact on Chronic Pain and Psychiatric Conditions-A Narrative Review.

Substance P (SP) plays a crucial role in pain modulation, with significant implications for major depressive disorder (MDD), anxiety disorders, and post-traumatic stress disorder (PTSD). Elevated SP levels are linked to heightened pain sensitivity and various psychiatric conditions, spurring interest in potential therapeutic interventions. In chronic pain, commonly associated with MDD and anxiety disorders, SP emerges as a key mediator in pain and emotional regulation. This review examines SP's impact on pain perception and its contributions to MDD, anxiety disorders, and PTSD. The association of SP with increased pain sensitivity and chronic pain conditions underscores its importance in pain modulation. Additionally, SP influences the pathophysiology of MDD, anxiety disorders, and PTSD, highlighting its potential as a therapeutic target. Understanding SP's diverse effects provides valuable insights into the mechanisms underlying these psychiatric disorders and their treatment. Further research is essential to explore SP modulation in psychiatric disorders and develop more effective treatment strategies.

Stress Affects Mast Cell Proteases in Murine Skin in a Model of Atopic Dermatitis-like Allergic Inflammation.

Stress exposure worsens allergic inflammatory diseases substantially. Mast cells (MCs) play a key role in peripheral immune responses to neuroendocrine stress mediators such as nerve growth factor (NGF) and substance P (SP). Mast cell proteases (MCPs) and cholinergic factors (Chrna7, SLURP1) were recently described to modulate MC stress response. We studied MCPs and Chrna7/SLURP1 and their interplay in a mouse model for noise induced stress (NiS) and atopic dermatitis-like allergic inflammation (AlD) and in cultured MC lacking Chrna7. We found that the cholinergic stress axis interacts with neuroendocrine stress mediators and stress-mediator cleaving enzymes in AlD. SP-cleaving mMCP4+ MC were upregulated in AlD and further upregulated by stress in NiS+AlD. Anti-NGF neutralizing antibody treatment blocked the stress-induced upregulation in vivo, and mMCP4+ MCs correlated with measures of AlD disease activity. Finally, high mMCP4 production in response to SP depended on Chrna7/SLURP1 in cultured MCs. In conclusion, mMCP4 and its upstream regulation by Chrna7/SLURP1 are interesting novel targets for the treatment of allergic inflammation and its aggravation by stress.

Substance P Promotes Leukocyte Infiltration in the Liver and Lungs of Mice with Sepsis: A Key Role for Adhesion Molecules on Vascular Endothelial Cells.

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 - a regulatory peptide with defense and repair functions. Results and perspectives for the fight against COVID-19.

Severe acute respiratory syndrome corona virus 2 (SARS CoV-2) is the cause of Corona virus disease 2019 (COVID-19), which turned into a pandemic in late 2019 and early 2020. SARS CoV-2 causes endothelial cell destruction and swelling, microthrombosis, constriction of capillaries, and malfunction of pericytes, all of which are detrimental to capillary integrity, angiogenesis, and healing processes. Cytokine storming has been connected to COVID-19 disease. Hypoxemia and tissue hypoxia may arise from impaired oxygen diffusion exchange in the lungs due to capillary damage and congestion. This personal view will look at how inflammation and capillary damage affect blood and tissue oxygenation, cognitive function, and the duration and intensity of COVID-19 disease. The general effects of microvascular injury, hypoxia, and capillary damage caused by COVID-19 in key organs are also covered in this point of view. Once initiated, this vicious cycle leads to diminished capillary function, which exacerbates inflammation and tissue damage, and increased inflammation due to hypoxia. Brain damage may result from low oxygen levels and high cytokines in brain tissue. In this paper we give a summary in this direction with focus on the role of the neuropeptide Substance P. On the basis of this, we discuss selected approaches to the question: "How Substance P is involved in the etiology of the COVID-19 and how results of our research could improve the prevention or therapy of corona? Thereby pointing out the role of Substance P in the post-corona syndrome and providing novel concepts for therapy and prevention.

The human major sublingual gland and its neuropeptidergic and nitrergic innervations.

BACKGROUND: What textbooks usually call the sublingual gland in humans is in reality a tissue mass of two types of salivary glands, the anteriorly located consisting of a cluster of minor sublingual glands and the posteriorly located major sublingual gland with its outlet via Bartholin's duct. Only recently, the adrenergic and cholinergic innervations of the major sublingual gland was reported, while information regarding the neuropeptidergic and nitrergic innervations is still lacking. METHODS: Bioptic and autoptic specimens of the human major sublingual gland were examined by means of immunohistochemistry for the presence of vasoactive intestinal peptide (VIP)-, neuropeptide Y (NPY)-, substance P (SP)-, calcitonin gene related-peptide (CGRP)-, and neuronal nitric oxide synthase (nNOS)-labeled neuronal structures. RESULTS: As to the neuropeptidergic innervation of secretory cells (here in the form of mucous tubular and seromucous cells), the findings showed many VIP-containing nerves, few NPY- and SP-containing nerves and a lack of CGRP-labeled nerves. As to the neuropeptidergic innervation of vessels, the number of VIP-containing nerves was modest, while, of the other neuropeptide-containing nerves under study, only few (SP and CGRP) to very few (NPY) nerves were observed. As to the nitrergic innervation, nNOS-containing nerves were very few close to secretory cells and even absent around vessels. CONCLUSION: The various innervation patterns may suggest potential transmission mechanisms involved in secretory and vascular responses of the major sublingual gland.

Amplifying endogenous stem cell migration for in situ bone tissue formation: Substance P analog and BMP mimetic peptide-loaded click-crosslinked hyaluronic acid hydrogel.

Endogenous stem cell-driven in situ bone tissue formation has recently garnered increasing attention. Therefore, our study sought to refine methods to enhance the migration and subsequent osteogenic differentiation of these cells. Our innovative approach involves using an injectable hydrogel that combines click cross-linking sites and a BMP-2 mimetic peptide (BP) with hyaluronic acid (HA). This injectable formulation, hereinafter referred to as SPa + Cx-HA-BP, incorporates a substance P analog peptide (SPa) with Cx-HA-BP, proving versatile for in vitro and in vivo applications without cytotoxicity. The controlled release of SPa creates a gradient that guides endogenous stem cells towards the Cx-HA scaffold from specific tissue niches. Both Cx-HA and SPa+Cx-HA induced minimal changes in the expression of genes associated with osteogenic differentiation. In contrast, these genes were robustly induced by both SPa + Cx-HA+BP and SPa + Cx-HA-BP, in which BP was respectively integrated via physical and chemical methods. Remarkably, chemically incorporating BP (Cx-HA-BP) resulted in 4-9 times higher osteogenic gene expression than physically mixed BP in Cx-HA+BP. This study validates the role of SPa role in guiding endogenous stem cells toward the hydrogel and underscores the substantial impact of sustained BP presence within the hydrogel. Collectively, our findings offer valuable insights for the development of innovative strategies to promote endogenous stem cell-based tissue regeneration. The developed hydrogel effectively guides stem cells from their natural locations and facilitates sustained osteogenic differentiation, thus holding great promise for applications in regenerative medicine.

Functional dissection of parabrachial substrates in processing nociceptive information.

Painful stimuli elicit first-line reflexive defensive reactions and, in many cases, also evoke second-line recuperative behaviors, the latter of which reflects the sensing of tissue damage and the alleviation of suffering. The lateral parabrachial nucleus (lPBN), composed of external- (elPBN), dorsal- (dlPBN), and central/superior-subnuclei (jointly referred to as slPBN), receives sensory inputs from spinal projection neurons and plays important roles in processing affective information from external threats and body integrity disruption. However, the organizational rules of lPBN neurons that provoke diverse behaviors in response to different painful stimuli from cutaneous and deep tissues remain unclear. In this study, we used region-specific neuronal depletion or silencing approaches combined with a battery of behavioral assays to show that slPBN neurons expressing substance P receptor ( NK1R) (lPBN NK1R) are crucial for driving pain-associated self-care behaviors evoked by sustained noxious thermal and mechanical stimuli applied to skin or bone/muscle, while elPBN neurons are dispensable for driving such reactions. Notably, lPBN NK1R neurons are specifically required for forming sustained somatic pain-induced negative teaching signals and aversive memory but are not necessary for fear-learning or escape behaviors elicited by external threats. Lastly, both lPBN NK1R and elPBN neurons contribute to chemical irritant-induced nocifensive reactions. Our results reveal the functional organization of parabrachial substrates that drive distinct behavioral outcomes in response to sustained pain versus external danger under physiological conditions.

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.

Specific Salivary Neuropeptides Shift Synchronously during Acute Stress in Fire Recruits.

Once thought of as an immune-privileged site, we now know that the nervous system communicates in a bidirectional manner with the immune system via the neuroimmune axis. Neuropeptides constitute a component of this axis, playing critical roles in the brain and periphery. The function of salivary neuropeptides in the acute stress response is not well understood. The purpose of this study is to investigate salivary neuropeptide levels during acute stress. Salivary samples were collected from fire recruits engaged in a stress training exercise previously shown to induce acute stress, at three separate timepoints during the exercise and levels of oxytocin, neurotensin, Substance P, α-MSH, and ß-Endorphin were measured using the Human Neuropeptide 5-Plex Custom Assay Eve Technologies. All neuropeptides increased throughout the acute stress simulation and during the recovery phase. Exploratory factor analysis (EFA) identified one factor contributing to baseline values across five neuropeptides and Pairwise Pearson Correlation Coefficient analysis showed positive correlations >0.9 for almost all neuropeptide combinations at the pre-stress timepoint. Further analysis identified negative and positive correlations between past-life trauma and self-assessed hardiness, respectively. Calculated neuropeptide scores showed an overall positive correlation to self-assessed hardiness. Altogether, our results suggest that salivary neuropeptides increase synchronously during acute stress and higher levels correlate with an increase in self-assessed hardiness. Further study is required to determine if interventions designed to enhance neuropeptide activity can increase stress resilience, especially in high-stress occupations such as firefighting.

Intervertebral disc injury triggers neurogenic inflammation of adjacent healthy discs.

BACKGROUND CONTEXT: Intervertebral disc degeneration is common and may play an important role in low back pain, but it is not well-understood. Previous studies have shown that the outer layer of the annulus fibrosus of a healthy disc is innervated by nociceptive nerve fibers. In the process of disc degeneration, it can grow into the inner annulus fibrosus or nucleus pulposus and release neuropeptides. Disc degeneration is associated with inflammation that produces inflammatory factors and potentiates nociceptor sensitization. Subsequently neurogenic inflammation is induced by neuropeptide release from activated primary afferent terminals. Because the innervation of a lumbar disc comes from multisegmental dorsal root ganglion neurons, does neurogenic inflammation in a degenerative disc initiate neurogenic inflammation in neighboring healthy discs by antidromic activity? PURPOSE: This study was based on animal experiments in Sprague-Dawley rats to investigate the role of neurogenic inflammation in adjacent healthy disc degeneration induced by disc injury. STUDY DESIGN: This was an experimental study. METHODS: Seventy-five 12-week-old, male Sprague-Dawley rats were allocated to 3 groups (sham group, disc injury group and disc injury+TrkA antagonist group). The disc injury group was punctured in the tail disc between the eighth and ninth coccygeal vertebrae (Co8-9) to establish an animal model of tail intervertebral disc degeneration. The sham group underwent only skin puncture and the disc injury+TrkA antagonist group was intraperitoneally injected with GW441756 two days before disc puncture. The outcome measure included quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay. RESULTS: Disc injury induced an increase in aggrecan, NGF, TrkA, CGRP, SP, IL-1ß, and IL-6 mRNA levels in the injured (Co8-9) and adjacent discs (Co7-8), which reached a peak on day 1, then gradually decreased, and returned to normal on day 14. After intraperitoneal injection of GW441756 prior to puncture, the mRNA levels of the above indicators were down-regulated in Co7-8 and Co8-9 intervertebral discs on the 1st and 7th days. The protein content of the above indicators in Co7-8 and Co8-9 intervertebral discs showed roughly the same trend as mRNA levels. CONCLUSIONS: Degeneration of one disc can induce neurogenic inflammation of adjacent healthy discs in a rat model. CLINICAL SIGNIFICANCE: This model supports a key role of neurogenic inflammation in disc degeneration, and may play a role in the experience of low back pain.

Yingxiang Acupoint Embedding Improves Mucosal Barrier Function in Rats with Local Allergic Rhinitis.

INTRODUCTION: Epithelial barrier disruption is the initial cause of various diseases. We previously reported that acupoint catgut embedding (AE) improves tight junction proteins (TJs) in rats with allergic rhinitis. However, whether AE improves the epithelial barrier in local allergic rhinitis (LAR) remains unknown. METHODS: A total of 36 Sprague Dawley (SD) male rats aged 5-7 weeks were divided into 6 groups with 6 rats each: control group, LAR model group, false acupoint embedding + LAR group, acupoint embedding + LAR group, capsaicin + LAR group, and tunicamycin + acupoint embedding + LAR group. Behavioral observation, ELISA to detect inflammatory factors in nasal lavage fluid and serum IgE, nasal mucosal permeability test, hematoxylin-eosin staining, PCR to detect Substance P (SP), Western blot, and immunofluorescence to detect endoplasmic reticulum stress (ERS) index and TJs were used to investigate the mechanism of AE in LAR. RESULTS: AE improved the symptoms and pathological features of nasal mucosa of LAR rats, reduced the inflammatory factors (IL4, IL5, IL13) of nasal lavage fluid, and showed no significant change in serum IgE levels in all groups. In addition, AE decreased the expression of SP in nasal mucosa of LAR rats, inhibited ERS, increased the expression of tight junction protein, reduced the permeability of nasal mucosa, and improved the function of nasal mucosal barrier. CONCLUSION: This study confirms that AE can improve the nasal mucosal barrier function of LAR by reducing the expression of SP, inhibiting ERS and increasing the expression of TJs, thus enhancing the nasal mucosal barrier function.