Three novel umami peptides derived from the alcohol extract of the Pacific oyster(Crassostrea gigas):identification,characterizations and interactions with T1R1/T1R3 taste receptors

Oyster(Crassostrea gigas),the main ingredient of oyster sauce,has a strong umami taste.In this study,three potential umami peptides,FLNQDEEAR(FR-9),FNKEE(FE-5),and EEFLK(EK-5),were identified and screened from the alcoholic extracts of the oyster using nano-HPLC-MS/MS analysis,i Umami-Scoring Card Method(i Umami-SCM)database and molecular docking(MD).Sensory evaluation and electronic tongue analysis were further used to confirm their tastes.The threshold of the three peptides ranged from 0.38 to 0.55 mg/m L.MD with umami receptors T1R1/T1R3 indicated that the electrostatic interaction and hydrogen bond interaction were the main forces involved.Besides,the Phe592 and Gln853 of T1R3 were the primary docking site for MD and played an important role in umami intensity.Peptides with two Glu residues at the terminus had stronger umami,especially at the C-terminus.These results contribute to the understanding of umami peptides in oysters and the interaction mechanism between umami peptides and umami receptors.

Effect of Marine Collagen Peptides on Markers of Metabolic Nuclear Receptors in Type 2 Diabetic Patients with/without Hypertension

Objective To explore Effects of marine collagen peptides （MCPs） on markers of metablic nuclear receptors, i.e peroxisome proliferator-activated receptor （PPARs）, liver X receptor （LXRs） and farnesoid X receptor （FXRs） in type 2 diabetic patients with/without hypertension. Method Study population consisted of 200 type 2 diabetic patients with/without hypertension and 50 healthy subjects, all of whom were randomly assigned to MCPs-treated diabetics （n=50）, placebo-treated diabetics （n=50）, MCPs-treated diabetics with hypertension （n=50）, placebo-treated diabetics with hypertension （n=50）, and healthy controls （n=50）. MCPs or placebo （water-soluble starch） were given daily before breakfast and bedtime over three months. Levels of free fatty acid, cytochrome P450, leptin, resistin, adiponectin, bradykinin, NO, and Prostacyclin were determined before intervention, and 1.5 months, and 3 months after intervention. Hypoglycemia and the endpoint events during the study were recorded and compared among the study groups. Result At the end of the study period, MCPs-treated patients showed marked improvement compared with patients receiving placebo. The protection exerted by MCPs seemed more profound in diabetics than in diabetics with hypertension. In particular, after MCPs intervention, levels of free fatty acid, hs-CRP, resistin, Prostacyclin decreased significantly in diabetics and tended to decrease in diabetic and hypertensive patients whereas levels of cytochrome P450, leptin, NO tended to decrease in diabetics with/without hypertension. Meanwhile, levels of adiponectin and bradykinin rose markedly in diabetics following MCPs administration. Conclusion MCPs could offer protection against diabetes and hypertension by affecting levels of molecules involved in diabetic and hypertensive pathogenesis. Regulation on metabolic nuclear receptors by MCPs may be the possible underlying mechanism for its observed effects in the study. Further study into its action may shed light on development of new drugs based on bioactive peptides from marine sources.

Potential PET Ligands for Imaging of Cerebral VPAC and PAC Receptors: Are Non-Peptide Small Molecules Superior to Peptide Compounds?

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) have been known for decades to mediate neuroendocrine and vasodilative actions via G-protein-coupled receptors of Class B. These are targets of imaging probes for positron emission tomography (PET) or single photon emission tomography (SPECT) in tumor diagnostics and tumor grading. However, they play only a subordinate role in the development of tracers for brain imaging. Difficulties in development of non-peptide ligands typical for cerebral receptors of PACAP and VIP are shared by all members of Class B receptor family. Essential landmarks have been confirmed for understanding of structural details of Class B receptor molecular signalling during the last five years. High relevance in the explanation of problems in ligand development for these receptors is admitted to the large N-terminal?ectodomain markedly different from Class A receptor binding sites and poorly suitable as orthosteric binding sites for the most small-molecule compounds. The present study is focused on the recently available receptor ligands for PAC1, VPAC1 and VPAC2 receptors as well as potential small-molecule lead structures suitable for use in PET or SPECT. Recently, biaryl, cyanothiophene and pentanamide structures with affinities in nM-range have been proposed as non-peptide ligands at VPAC1 and VPAC2 receptors. However, most of these ligands have been classified as non-competitive related to the orthosteric binding site of endogenous peptide ligands of VPAC receptors. For PAC1 receptors have been identified hydrazide compounds for which an inhibitory and potentially competitive mechanism of receptor binding has been postulated based on molecular docking studies.

The N-formyl peptide receptors: contemporary roles in neuronal function and dysfunction

N-formyl peptide receptors(FPRs)were first identified upon phagocytic leukocytes,but more than four decades of research has unearthed a plethora of non-myeloid roles for this receptor family.FPRs are expressed within neuronal tissues and markedly in the central nervous system,where FPR interactions with endogenous ligands have been implicated in the pathophysiology of several neurodegenerative diseases including Alzheimer's disease and Parkinson's disease,as well as neurological cancers such as neuroblastoma.Whilst the homeostatic function of FPRs in the nervous system is currently undefined,a variety of novel physiological roles for this receptor family in the neuronal context have been posited in both human and animal settings.Rapid developments in recent years have implicated FPRs in the process of neurogenesis and neuronal differentiation which,upon greater characterisation,could represent a novel pharmacological target for neuronal regeneration therapies that may be used in the treatment of brain/spinal cord injury,stroke and neurodegeneration.This review aims to summarize the recent progress made to determine the physiological role of FPRs in a neuronal setting,and to put forward a case for FPRs as a novel pharmacological target for conditions of the nervous system,and for their potential to open the door to novel neuronal regeneration therapies.

Signal Peptide and Denaturing Temperature are Critical Factors for Efficient Mammalian Expression and Immunoblotting of Cannabinoid Receptors

Many researchers employed mammalian expression system to artificially express cannabinoid receptors, but immunoblot data that directly prove efficient protein expression can hardly be seen in related research reports. In present study, we demonstrated cannabinoid receptor protein was not able to be properly expressed with routine mammalian expression system. This inefficient expression was rescued by endowing an exogenous signal peptide ahead of cannabinoid receptor peptide. In addition, the artificially synthesized cannabinoid receptor was found to aggregate under routine sample denaturing temperatures (i.e.,≥95°C), forming a large molecular weight band when analyzed by immuno-blotting. Only denaturing temperatures ≤75°C yielded a clear band at the predicted molecular weight. Collectively, we showed that efficient mammalian expression of cannabinoid receptors need a signal peptide sequence, and described the requirement for a low sample denaturing temperature in immuno-blot analysis. These findings provide very useful information for efficient mammalian expression and immuno-blotting of membrane receptors.

THE EXPRESSION OF RECEPTORS FOR VASOACTIVE INTESTINAL PEPTIDE AND SECRETIN IN COLON NEOPLASMS

Objective: To investigate the expression of the receptors for vasoactive intestinal peptide (VIP) and secretin in colon cancer. Methods: This study visualized and characterized the receptors for VIP and secretin in the sequence of human tumor-free colon, adenoma, carcinoma, liver metastasis using storage phosphor autoradiography. Results: Receptors for VIP and secretin were demonstrated in tumor-free colon and colon tumors. A decrease in affinity of VIP receptors was shown in the colonic liver metastasis (Kd = 3.30 nmol) when compared with tumor-free colon (Kd = 0.82 nmol). An up-regulation of receptors for secretin was found in colonic liver metastases. Conclusions: VIP and secretin were both expressed on normal colon tissues. Binding of VIP decreased while secretin increased in colonic liver metastasis. A down-regulation of receptors for VIP in colonic liver metastases may helpful to understand the migration of colon cancer.

Small-Molecule Ligands as Challenge for Positron Emission Tomography of Peptide Receptors in Neurons and Microglia of the Brain

Neuropeptide and chemokine receptors of the G protein-coupled receptor (GPCR) family belong to different classes and subgroups providing different docking sites and special binding behavior at extracellular and also transmembrane domains for small molecules potentially suitable for positron emission tomography (PET). The contribution gives an overview updating developments of small-molecule, nonpeptide ligands at a selection of peptide and chemokine receptors, expressed in neurons and microglia of the brain, regarding the last five years. Orexin 1 and orexin 2 receptors (OX1R;OX2R) and neuropeptide Y1 and Y2 receptors (NPY1R, NPY2R) were chosen as representatives of Class A neuropeptide receptors, chemokine receptor CX3C (CX3CR1) as Class A, protein-activated receptor, highly expressed in activated microglia, and corticotropin releasing factor receptor 1 (CRFR1) as representative Class B1 receptor. Structural differences between binding domains and their endogenous ligands as well as parallel expression in different types of cells and generally low density of these receptors in brain tissue are factors making the search for selective and sensitive ligands more difficult than for classical GPCR receptors. Main progress in ligand development is observed for NPY receptor antagonists and orexin receptor antagonists. For orexin receptors, search for suitable ligands can be supported with modelling approaches, as recently the complete molecular structure of these receptors is available. Small molecules, binding at CRFR1, as for other Class B1 receptor ligands, in PET and investigations of pharmacodynamics revealed rather allosteric binding modes, although, the complete crystal structure of CRFR1 as prototype of Class B1 provides, hitherto, improved possibilities for understanding binding mechanisms. Highly specific as a marker of microglia among?the GPCRs, CX3CR1 is focused as target of PET during inflammation of brain and spinal cord.

Olfactory receptors in neural regeneration in the central nervous system

Olfactory receptors are crucial for detecting odors and play a vital role in our sense of smell,influencing behaviors from food choices to emotional memories.These receptors also contribute to our perception of flavor and have potential applications in medical diagnostics and environmental monitoring.The ability of the olfactory system to regenerate its sensory neurons provides a unique model to study neural regeneration,a phenomenon largely absent in the central nervous system.Insights gained from how olfactory neurons continuously replace themselves and reestablish functional connections can provide strategies to promote similar regenerative processes in the central nervous system,where damage often results in permanent deficits.Understanding the molecular and cellular mechanisms underpinning olfactory neuron regeneration could pave the way for developing therapeutic approaches to treat spinal co rd injuries and neurodegenerative diseases like Alzheimer's disease.Olfa ctory receptors are found in almost any cell of eve ry orga n/tissue of the mammalian body.This ectopic expression provides insights into the chemical structures that can activate olfactory receptors.In addition to odors,olfactory receptors in ectopic expression may respond to endogenous compounds and molecules produced by mucosal colonizing microbiota.The analysis of the function of olfactory receptors in ectopic expression provides valuable information on the signaling pathway engaged upon receptor activation and the receptor's role in proliferation and cell differentiation mechanisms.This review explo res the ectopic expression of olfa ctory receptors and the role they may play in neural regeneration within the central nervous system,with particular attention to compounds that can activate these receptors to initiate regenerative processes.Evidence suggests that olfactory receptors could serve as potential therapeutic targets for enhancing neural repair and recovery following central nervous system injuries.

Non-peptide ligands in the characterization of peptide receptors at the interface between neuroendocrine and mental diseases

Hypothalamic receptors for neuropeptide Y, melaninconcentrating hormone, melanocortins and orexins/ hypocretins as well as for the downstream signaling corticotrophic factor have been discussed broadly for their influence on food intake and reward but also on several psychiatric disorders. For the development of non-peptide ligands for the in vivo detection of alterations in density and affinity of such G-protein coupled (GPCRs) peptide receptors the requirements to affinity and pharmacokinetics have been shifted to thresholds markedly distict from classical GPCRs to dissociation constants ported originally as potential therapeutics in the treatment of obesity among which some are suitable candidates for labeling as PET or SPECT-tracers providing receptor affinities even below 0.1 nM. These could be unique tools not only for better understanding of the mechanism of obesity but also for investigations of extrahypothalamic role of “feeding receptors” at the interface between neuroendocrine and mental diseases.

Vasoactive Intestinal Peptide (VIP) and VIP Receptors-Elucidation of Structure and Function for Therapeutic Applications

Vasoactive intestinal peptide (VIP) is a 28-amino acid polypeptide first isolated from swine duodenum. VIP is a neurotransmitter that is extensively distributed in tissues. According to published reports, VPAC1 and VPAC2 act as VIP receptors and are widely present in the central nervous system and peripheral tissues. VIP exerts diverse actions on the cardiovascular system, pancreas, digestive tract, respiratory system, and urological system. Recent reports indicated that VIP has immunological and neuroprotective effects and also affects cell growth. While primary investigations for developing therapeutic applications for various pathological conditions and diseases are underway, the structure and function of VIP should be analyzed in more detail.

Coagonist of glucagon-like peptide-1 and glucagon receptors ameliorates kidney injury in murine models of obesity and diabetes mellitus

AIM To investigate the role of glucagon-like peptide-1(GLP-1)/glucagon receptors coagonist on renal dysfunction associated with diabetes and obesity. METHODS Chronic high-fat diet fed C57 BL/6 J mice, streptozotocintreated high-fat diet fed C57 BL/6 J mice and diabeticC57 BLKS/J db/db mice were used as models of diabetes-induced renal dysfunction. The streptozotocintreated high-fat diet fed mice and db/db mice were treated with the GLP-1 and glucagon receptors coagonist(Aib2 C24 Chimera2, 150 μg/kg, sc) for twelve weeks, while in chronic high-fat diet fed mice, coagonist(Aib2 C24 Chimera2, 150 μg/kg, sc) treatment was continued for forty weeks. Kidney function, histology, fibrosis, inflammation, and plasma biochemistry were assessed at the end of the treatment. RESULTS Coagonist treatment decreased body weight, plasma lipids, insulin resistance, creatinine, blood urea nitrogen, urinary albumin excretion rate and renal lipids. In kidney, expression of lipogenic genes(SREBP-1 C, FAS, and SCD-1) was decreased, and expression of genes involved in β-oxidation(CPT-1 and PPAR-α) was increased due to coagonist treatment. In plasma, coagonist treatment increased adiponectin and FGF21 and decreased IL-6 and TNF-?. Coagonist treatment reduced expression of inflammatory(TNF-α, MCP-1, and MMP-9) and pro-fibrotic(TGF-β, COL1 A1, and α-SMA) genes and also improved histological derangement in renal tissue.CONCLUSION Coagonist of GLP-1 and glucagon receptors alleviated diabetes and obesity-induced renal dysfunction by reducing glucose intolerance, obesity, and hyperlipidemia.

C-type natriuretic peptide stimulates chicken myoblast differentiation through NPRB/NPRC receptors and metabolism pathway

Skeletal muscle development is closely related with the amount of meat production and its quality in chickens. Natriuretic peptides(NPs) play an important role in myotube formation and fat oxidation of skeletal muscle in animals. The effect of C-type natriuretic peptide(CNP), an important member of the NPs, and its underlying molecular mechanisms in skeletal muscle are incompletely understood. Treatment of myoblasts with CNP led to enhanced proliferation/differentiation and significantly upregulated(P<0.05) m RNA expression of the CNP receptors natriuretic peptide receptor B(NPRB) and the clearance receptor C(NPRC). In cells exposed to CNP, 142 differentially expressed genes(84 up-regulation and 58 down-regulation)(P<0.05) were identified by RNA-sequencing compared with those in control cells. Sixteen genes were significantly enriched(P<0.05) in the metabolic pathway, and six of them(phospholipase C β4, phospholipase C β2, phosphoglycerate mutase 1, creatine kinase B, peroxiredoxin 6 and CD38) were closely related to skeletal muscle development and differentially expressed. In conclusion, CNP stimulated differentiation of myoblasts by upregulating expression of the NPRB and NPRC receptors and enriching key genes in the metabolic pathway.

A matrix metalloproteinase-responsive hydrogel system controls angiogenic peptide release for repair of cerebral ischemia/reperfusion injury

Vascular endothelial growth factor and its mimic peptide KLTWQELYQLKYKGI(QK)are widely used as the most potent angiogenic factors for the treatment of multiple ischemic diseases.However,conventional topical drug delivery often results in a burst release of the drug,leading to transient retention(inefficacy)and undesirable diffusion(toxicity)in vivo.Therefore,a drug delivery system that responds to changes in the microenvironment of tissue regeneration and controls vascular endothelial growth factor release is crucial to improve the treatment of ischemic stroke.Matrix metalloproteinase-2(MMP-2)is gradually upregulated after cerebral ischemia.Herein,vascular endothelial growth factor mimic peptide QK was self-assembled with MMP-2-cleaved peptide PLGLAG(TIMP)and customizable peptide amphiphilic(PA)molecules to construct nanofiber hydrogel PA-TIMP-QK.PA-TIMP-QK was found to control the delivery of QK by MMP-2 upregulation after cerebral ischemia/reperfusion and had a similar biological activity with vascular endothelial growth factor in vitro.The results indicated that PA-TIMP-QK promoted neuronal survival,restored local blood circulation,reduced blood-brain barrier permeability,and restored motor function.These findings suggest that the self-assembling nanofiber hydrogel PA-TIMP-QK may provide an intelligent drug delivery system that responds to the microenvironment and promotes regeneration and repair after cerebral ischemia/reperfusion injury.

Cortico-striatal gamma oscillations are modulated by dopamine D3 receptors in dyskinetic rats

Long-term levodopa administration can lead to the development of levodopa-induced dyskinesia.Gamma oscillations are a widely recognized hallmark of abnormal neural electrical activity in levodopa-induced dyskinesia.Currently,studies have reported increased oscillation power in cases of levodopa-induced dyskinesia.However,little is known about how the other electrophysiological parameters of gamma oscillations are altered in levodopa-induced dyskinesia.Furthermore,the role of the dopamine D3 receptor,which is implicated in levodopa-induced dyskinesia,in movement disorder-related changes in neural oscillations is unclear.We found that the cortico-striatal functional connectivity of beta oscillations was enhanced in a model of Parkinson’s disease.Furthermore,levodopa application enhanced cortical gamma oscillations in cortico-striatal projections and cortical gamma aperiodic components,as well as bidirectional primary motor cortex(M1)↔dorsolateral striatum gamma flow.Administration of PD128907(a selective dopamine D3 receptor agonist)induced dyskinesia and excessive gamma oscillations with a bidirectional M1↔dorsolateral striatum flow.However,administration of PG01037(a selective dopamine D3 receptor antagonist)attenuated dyskinesia,suppressed gamma oscillations and cortical gamma aperiodic components,and decreased gamma causality in the M1→dorsolateral striatum direction.These findings suggest that the dopamine D3 receptor plays a role in dyskinesia-related oscillatory activity,and that it has potential as a therapeutic target for levodopa-induced dyskinesia.

Practical guide:Glucagon-like peptide-1 and dual glucosedependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonists in diabetes mellitus

Practical guide:Glucagon-like peptide-1 and dual glucosedependent insulinotropic polypeptide and glucagon-like peptide-1 receptor agonists in diabetes mellitus common second-line choice after metformin for treating T2DM.Various considerations can make selecting and switching between different GLP-1 RAs challenging.Our study aims to provide a comprehensive guide for the usage of GLP-1 RAs and dual GIP and GLP-1 RAs for the management of T2DM.

Neuropeptide Receptors in Pain Circuitries: Useful Targets for CNS Imaging with Non-Peptide Ligands Suitable for PET?

Neuropeptide receptors of the brain and spinal cord are parts of the pain circuits targeted by analgesic drugs. Some of these receptors have been found in the central nervous system as well as in intracranial vascular structures and achieved revival of attention because of their role in acute and chronic pain syndromes. A number of them are of high clinical relevance for e.g. migraine. Others participate in symptoms of rare diseases like amyotrophic lateral sclerosis. Here we will focus on five of the neuropeptide receptors and their non-peptide ligands potentially or already successfully used as PET probes. Opioid receptors and neurotensin receptors are known to mediate analgesic actions. Bradykinin and calcitonin gene-related peptide (CGRP) receptors are known to be involved in the regulation of vascular tone and inflammatory responses, and neurokinin receptors play a role in the occurrence of pain perception in a rather indirect manner. Most experiences as PET tracers have been gathered with opioid receptor ligands and neurokinin receptor ligands. The most innovative fields revealed by the studies summarized in this report are the ligands of κ opioid receptors and CGRP receptors for which a first PET tracer was presented recently.

Novel umami peptides from two Termitomyces mushrooms and molecular docking to the taste receptor T1R1/T1R3

Wild edible Termitomyces mushrooms are popular in Southwest China and umami is important flavor qualities of edible mushrooms.This study aimed to understand the umami taste of Termitomyces intermedius and Termitomyces aff.bulborhizus.Ten umami peptides from aqueous extracts were separated using a Sephadex G-15 gel filtration chromatography.The intense umami fraction was evaluated by both sensory evaluation and electronic tongue.They were identified as KLNDAQAPK,DSTDEKFLR,VGKGAHLSGEH,MLKKKKLA,SLGFGGPPGY,TVATFSSSTKPDD,AMDDDEADLLLLAM,VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK.Seven peptides,except VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK were selectively synthesized to verify their taste characteristics.All these 10 peptides had umami or salt taste.The 10 peptides were conducted by molecular docking to study their interaction with identified peptides and the umami taste receptor T1R1/T1R3.All these 10 peptides perfectly docked the active residues in the T1R3 subunit.Our results provide theoretical basis for the umami taste and address the umami mechanism of two wild edible Termitomyces mushrooms.

Calcium-chelating peptides from rabbit bone collagen:characterization,identification and mechanism elucidation

This study aimed to characterize and identify calcium-chelating peptides from rabbit bone collagen and explore the underlying chelating mechanism.Collagen peptides and calcium were extracted from rabbit bone by instant ejection steam explosion(ICSE)combined with enzymatic hydrolysis,followed by chelation reaction to prepare rabbit bone peptide-calcium chelate(RBCP-Ca).The chelating sites were further analyzed by liquid chromatography-tandem mass(LC-MS/MS)spectrometry while the chelating mechanism and binding modes were investigated.The structural characterization revealed that RBCP successfully chelated with calcium ions.Furthermore,LC-MS/MS analysis indicated that the binding sites included both acidic amino acids(Asp and Glu)and basic amino acids(Lys and Arg),Interestingly,three binding modes,namely Inter-Linking,Loop-Linking and Mono-Linking were for the first time found,while Inter-Linking mode accounted for the highest proportion(75.1%),suggesting that chelation of calcium ions frequently occurred between two peptides.Overall,this study provides a theoretical basis for the elucidation of chelation mechanism of calcium-chelating peptides.

Exploring the taste presentation and receptor perception mechanism of salty peptides from Stropharia rugosoannulata based on molecular dynamics and thermodynamics simulation

The taste presentation and receptor perception mechanism of the salty peptide of Stropharia rugosoannulata were predicted and verified using peptide omics and molecular interaction techniques.The combination of aspartic acid(D)and glutamic acid(E),or peptide fragments composed of arginine(R),constitute the characteristic taste structural basis of salty peptides of S.rugosoannulata.The taste intensity of the salty peptide positively correlates with its concentration within a specific concentration range(0.25–1.0 mg/mL).The receptor more easily recognizes the first amino acid residue at the N-terminal of salty peptides and the aspartic acid residue in the peptides.GLU513,ASP707,and VAL508 are the critical amino acid residues for the receptor to recognize salty peptides.TRPV1 is specifically the receptor for recognizing salty peptides.Hydrogen bonds and electrostatic interactions are the main driving forces for the interactions between salty peptides and TRPV1 receptors.KSWDDFFTR has the most potent binding capacity with the receptor and has tremendous potential for application in sodium salt substitution.This study confirmed the taste receptor that specifically recognizes salty peptides,analyzed the receptor-peptide binding interaction,and provided a new idea for understanding the taste receptor perception of salty peptides.

Neutrophil peptide 1 accelerates the clearance of degenerative axons during Wallerian degeneration by activating macrophages after peripheral nerve crush injury

Macrophages play an important role in peripheral nerve regeneration,but the specific mechanism of regeneration is still unclear.Our preliminary findings indicated that neutrophil peptide 1 is an innate immune peptide closely involved in peripheral nerve regeneration.However,the mechanism by which neutrophil peptide 1 enhances nerve regeneration remains unclear.This study was designed to investigate the relationship between neutrophil peptide 1 and macrophages in vivo and in vitro in peripheral nerve crush injury.The functions of RAW 264.7 cells we re elucidated by Cell Counting Kit-8 assay,flow cytometry,migration assays,phagocytosis assays,immunohistochemistry and enzyme-linked immunosorbent assay.Axonal debris phagocytosis was observed using the CUBIC(Clear,Unobstructed Brain/Body Imaging Cocktails and Computational analysis)optical clearing technique during Wallerian degeneration.Macrophage inflammatory factor expression in different polarization states was detected using a protein chip.The results showed that neutrophil peptide 1 promoted the prolife ration,migration and phagocytosis of macrophages,and CD206 expression on the surfa ce of macrophages,indicating M2 polarization.The axonal debris clearance rate during Wallerian degeneration was enhanced after neutrophil peptide 1 intervention.Neutrophil peptide 1 also downregulated inflammatory factors interleukin-1α,-6,-12,and tumor necrosis factor-αin invo and in vitro.Thus,the results suggest that neutrophil peptide 1 activates macrophages and accelerates Wallerian degeneration,which may be one mechanism by which neutrophil peptide 1 enhances peripheral nerve regeneration.