Substance P enhances cellular migration and inhibits senescence in human dermal fibroblasts under hyperglycemic conditions

Exploring the interplay between stress mediators and skin microbiota in shaping age-related hallmarks: A review

Psychological stress is a major contributing factor to several health problems (e.g., depression, cardiovascular disease). Around 35 % of the world's population suffers from it, including younger generations. Physiologically, stress manifests through neuroendocrine pathways (Hypothalamic-Pituitary-Adrenal (HPA) axis and Sympathetic-Adrenal-Medullary (SAM) system) which culminate in the production of stress mediators like cortisol, epinephrine and norepinephrine. Stress and its mediators have been associated to body aging, through molecular mechanisms such as telomere attrition, mitochondrial dysfunction, cellular senescence, chronic inflammation, and dysbiosis, among others. Regarding its impact in the skin, stress impacts its structural integrity and physiological function. Despite this review focusing on several hallmarks of aging, emphasis was placed on skin microbiota dysbiosis. In this line, several studies, comprising different age groups, demographic contexts and body sites, have reported skin microbiota alterations associated with aging, and some effects of stress mediators on skin microbiota have also been reviewed in this paper. From a different perspective, since it is not a "traditional" stress mediator, oxytocin, a cortisol antagonist, has been related to glucorticoids inhibition and to display positive effects on cellular aging. This hormone dysregulation has been associated to psychological issues such as depression, whereas its upregulation has been linked to positive social interaction.

Preconditioning with Substance P Restores Therapeutic Efficacy of Aged ADSC by Elevating TNFR2 and Paracrine Potential

Aging leads to a decline in stem cell activity by reducing the repopulation rate and paracrine potential, ultimately diminishing efficacy in vivo. TNF-α can exert inflammatory and cell death actions via Erk by binding to TNFR-1, and survival and tissue repair actions via Akt by binding to TNFR-2. Aged cells are reported to have insufficient expression of TNFR-2, indicating that aged adipose-derived stem cells (ADSCs-E) lack the ability for cell survival and immune control compared to young ADSCs (ADSCs-Y). This study aims to assess the preconditioning effect of SP on the response of ADSCs-E to inflammation. ADSCs-E were treated with SP and then exposed to a high dose of TNF-α for 24 h. Consequently, ADSC-E exhibited weaker viability and lower TNFR2 levels compared to ADSC-Y. In response to TNF-α, the difference in TNFR2 expression became more pronounced in ADSC-E and ADSC-Y. Moreover, ADSC-E showed a severe deficiency in proliferation and paracrine activity. However, preconditioning with SP significantly enhanced the viability of ADSCs-E and also restored TNFR2 expression and paracrine potential, similar to ADSC-Y under inflammatory conditions. Our findings support the idea that preconditioning with SP has the potential to restore the cellular function of senescent stem cells before transplantation.

Unripe Carica papaya Fresh Fruit Extract Protects against Methylglyoxal-Mediated Aging in Human Dermal Skin Fibroblasts

The glycolytic metabolite methylglyoxal (MGO) initiates the formation of advanced glycation end products and oxidative stress, leading to cellular senescence and skin aging. This study focuses on the anti-aging properties of unripe Carica papaya L. (UCP) fresh fruit extract on MGO-induced human dermal fibroblast senescence. We pretreated human foreskin fibroblasts with UCP before incubating them with MGO (400 μM) for 72 h. We used the glycation inhibitor aminoguanidine hydrochloride (AG) as the positive control. Senescent fibroblasts were detected using senescence-associated beta-galactosidase activity and collagen type I expression (COL1A1). We investigated the changes in the Akt, JNK/p38 mitogen-activated protein kinase (MAPK), c-Jun, and nuclear factor kappa B (NF-κB) signaling pathways using Western blotting. UCP significantly suppressed MGO-induced senescent fibroblasts (from 20.90±2.00% to 11.78±2.04%) when compared with the baseline level at 7.10±0.90% (P<0.05). While COL1A1 was diminished by 43.35±1.56% (P<0.001) in the MGO-treated fibroblasts, UCP and AG could recover COL1A1 to 63.22±4.78% and 64.39±3.34%, respectively. MGO triggered overactivation of Akt, JNK/p38 MAPK, c-Jun, and NF-κB by 2.10±0.09, 8.10±0.37, 6.60±0.29, 2.18±0.23, and 3.74±0.37 folds, respectively. UCP and AG significantly abolished these changes. Consistently, MGO increased matrix metalloproteinase-1 (MMP-1) levels by 2.58±0.04 folds, which was significantly suppressed by UCP and AG pretreatment to 1.87±0.11 and 1.69±0.07 folds, respectively. In summary, UCP controlled MGO-induced fibroblast senescence by suppressing the JNK/c-Jun/MMP and p38/NF-κB/COL1A1 pathways, similar to the action of the glycation inhibitor AG. Therefore, UCP can be considered a functional fruit for preventing and delaying skin aging.

Neuropeptide substance P: A promising regulator of wound healing in diabetic foot ulcers

In the past, neuropeptide substance P (SP) was predominantly recognized as a neuroinflammatory factor, while its potent healing activity was overlooked. This paper aims to review the regulatory characteristics of neuropeptide SP in both normal and diabetic wound healing. SP actively in the regulation of wound healing-related cells directly and indirectly, exhibiting robust inflammatory properties, promoting cell proliferation and migration and restoring the activity and paracrine ability of skin cells under diabetic conditions. Furthermore, SP not only regulates healing-related cells but also orchestrates the immune environment, thereby presenting unique and promising application prospects in wound intervention. As new SP-based preparations are being explored, SP-related drugs are poised to become an effective therapeutic intervention for diabetic foot ulcers (DFU).

Regulation of Cellular Senescence in Type 2 Diabetes Mellitus: From Mechanisms to Clinical Applications

Cellular senescence is accelerated by hyperglycemia through multiple pathways. Therefore, senescence is an important cellular mechanism to consider in the pathophysiology of type 2 diabetes mellitus (T2DM) and an additional therapeutic target. The use of drugs that remove senescent cells has led to improvements in blood glucose levels and diabetic complications in animal studies. Although the removal of senescent cells is a promising approach for the treatment of T2DM, two main challenges limit its clinical application: the molecular basis of cellular senescence in each organ is yet to be understood, and the specific effect of removing senescent cells in each organ has to be determined. This review aims to discuss future applications of targeting senescence as a therapeutic option in T2DM and elucidate the characteristics of cellular senescence and senescence-associated secretory phenotype in the tissues important for regulating glucose levels: pancreas, liver, adipocytes, and skeletal muscle.

Substance P reversibly compromises the integrity and function of blood-brain barrier

BACKGROUND

Substance P (SP) plays a role in vasodilatation and tissue integrity through its receptor, neurokinin 1 (NK1R). However, its specific effect on blood-brain barrier (BBB) remains unknown.

METHODS

The impact of SP on the integrity/function of human BBB model in vitro, composed of brain microvascular endothelial cells (BMECs), astrocytes and pericytes, was assessed by measurements of transendothelial electrical resistance and paracellular flux of sodium fluorescein (NaF), respectively in the absence/presence of specific inhibitors targeting NK1R (CP96345), Rho-associated protein kinase (ROCK; Y27632) and nitric oxide synthase (NOS; N(G)-nitro-L-arginine methyl ester). Sodium nitroprusside (SNP), a NO donor, was employed as a positive control. The levels of tight junction proteins, zonula occludens-1, occludin and claudin-5 alongside RhoA/ROCK/myosin regulatory light chain-2 (MLC2) and extracellular signal‑regulated protein kinase (Erk1/2) proteins were detected by western analyses. Subcellular localisations of F-actin and tight junction proteins were visualized by immunocytochemistry. Flow cytometry was used to detect transient calcium release.

RESULTS

Exposure to SP increased RhoA, ROCK2 and phosphorylated serine-19 MLC2 protein levels and Erk1/2 phosphorylation in BMECs which were abolished by CP96345. These increases were independent of the changes in intracellular calcium availability. SP perturbed BBB in a time-dependent fashion through induction of stress fibres. Changes in tight junction protein dissolution or relocalisation were not involved in SP-mediated BBB breakdown. Inhibition of NOS, ROCK and NK1R mitigated the effect of SP on BBB characteristics and stress fibre formation.

CONCLUSION

SP promoted a reversible decline in BBB integrity independent of tight junction proteins expression or localisation.

The neuropeptide substance P/neurokinin-1 receptor system and diabetes: From mechanism to therapy

Diabetes is a significant public health issue known as the world's fastest-growing disease condition. It is characterized by persistent hyperglycemia and subsequent chronic complications leading to organ dysfunction and, ultimately, the failure of target organs. Substance P (SP) is an undecapeptide that belongs to the family of tachykinin (TK) peptides. The SP-mediated activation of the neurokinin 1 receptor (NK1R) regulates many pathophysiological processes in the body. There is also a relation between the SP/NK1R system and diabetic processes. Importantly, deregulated expression of SP has been reported in diabetes and diabetes-associated chronic complications. SP can induce both diabetogenic and antidiabetogenic effects and thus affect the pathology of diabetes destructively or protectively. Here, we review the current knowledge of the functional relevance of the SP/NK1R system in diabetes pathogenesis and its exploitation for diabetes therapy. A comprehensive understanding of the role of the SP/NK1R system in diabetes is expected to shed further light on developing new therapeutic possibilities for diabetes and its associated chronic conditions.

Mesenchymal stem cells pretreated with proinflammatory cytokines accelerate skin wound healing by promoting macrophages migration and M2 polarization

Introduction

Methods

Results

Conclusions

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We found that S-IT MSCs were better at promoting macrophage migration and activation than S-MSCs in vitro.

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Next, we reconfirmed that S-IT MSCs were more effective than S-MSCs in accelerating wound closure by promoting macrophage migration and activation.

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High levels of CCL2 and IL-6 in S-IT MSCs may play a key role in improving macrophage function.

The conditioned medium from mesenchymal stromal cells pretreated with proinflammatory cytokines promote fibroblasts migration and activation

Human dermal fibroblasts (HDFs) play important roles in all stages of wound healing. However, in nonhealing wounds, fibroblasts are prone to aging, resulting in insufficient migration, proliferation and secretion functions. Recent studies have suggested that mesenchymal stromal cells (MSCs) are conducive to wound healing and cell growth through paracrine cytokine signaling. In our studies, we found that conditioned medium of MSCs pretreated with IFN-γ and TNF-α (IT MSC-CM) has abundant growth factors associated with wound repair. Our in vitro results showed that the effects of IT MSC-CM on promoting cell migration, proliferation and activation in HDFs were better than those of conditioned medium from mesenchymal stromal cells (MSC-CM). Moreover, we embedded a scaffold material containing IT MSC-CM and reconfirmed that cell migration and activation were superior to that in the presence of MSC-CM in vivo. Generally, PDGF-BB is perceived as a promoter of the migration and proliferation of HDFs. Moreover, a high level of PDGF-BB in IT MSC-CM was detected, according to which we guess that the effect on HDFs may be mediated by the upregulation of PDGF-BB. These studies all showed the potential of IT MSC-CM to promote rapid and effective wound healing.

A review of diabetic wound models-Novel insights into diabetic foot ulcer

Diabetic foot ulcer (DFU) is a major debilitating complication of diabetes. Many research investigations have been conducted with the aims to uncover the diabetic wound healing mechanisms, develop novel therapeutics, and screen bioactive wound dressings in order to improve the current management of DFU. These would have not been possible without the utilization of an appropriate wound model, especially in a diabetic wound context. This review focuses on the different in vitro research models used in DFU investigations such as the 2D scratch wound assay, 3D skin model, and 3D angiogenesis model as well as their limitations. The current efforts and challenges to apply the 2D and 3D in vitro models in a hyperglycemic context to provide insights into DFU modeling will be reviewed. Perspectives of utilizing 3D bioprinting and skin-on-the-chip model as a diabetic wound model in the future will also be highlighted. By leveraging knowledge from past experiences and current research, an improved experimental model for DFU is anticipated to be established in near future.

Neuropeptide Substance P Enhances Skin Wound Healing In Vitro and In Vivo under Hypoxia

Pressure ulcers (PUs) or sores are a secondary complication of diabetic neuropathy and traumatic spinal cord injury (SCI). PUs tend to occur in soft tissues located around bony prominences and may heal slowly or not at all. A common mechanism underlying impaired healing of PUs may be dysfunction of the local neurovascular system including deficiency of essential neuropeptides, such as substance P (SP). Previous studies indicate that disturbance in cutaneous sensory innervation leads to a defect in all stages of wound healing, as is the case after SCI. It is hypothesized that nerve fibers enhance wound healing by promoting initial inflammation via the releasing of neuropeptides such as SP. Therefore, we investigated whether exogenous SP improves skin wound healing using in vitro and in vivo models. For in vitro studies, the effects of SP on keratinocyte proliferation and wound closure after a scratch injury were studied under normoxia (pO₂ ~21%) or hypoxia (pO₂ ~1%) and in presence of normal serum (10% v/v) or low serum (1% v/v) concentrations. Hypoxia and low serum both significantly slowed cell proliferation and wound closure. Under combined low serum and hypoxia, used to mimic the nutrient- and oxygen-poor environment of chronic wounds, SP (10⁻⁷ M) significantly enhanced cell proliferation and wound closure rate. For in vivo studies, two full-thickness excisional wounds were created with a 5 mm biopsy punch on the dorsum on either side of the midline of 15-week-old C57BL/6J male and female mice. Immediately, wounds were treated topically with one dose of 0.5 μg SP or PBS vehicle. The data suggest a beneficial role in wound closure and reepithelization, and thus enhanced wound healing, in male and female mice. Taken together, exogenously applied neuropeptide SP enhanced wound healing via cell proliferation and migration in vitro and in vivo. Thus, exogenous SP may be a useful strategy to explore further for treating PUs in SCI and diabetic patients.

Diacetoxyscirpenol-induced heterophil extracellular traps contribute to the immune toxicity of liver injury in chickens

Diacetoxyscirpenol (DAS) is one kind of type A trichothecene mycotoxin which produced by Fusarium species which contaminates agricultural crops and food. DAS attracts particular attention because of the strong toxicity. Heterophil extracellular traps (HETs) is a defense mechanism in the chicken innate immune. In this study, we firstly examine the effects and molecular mechanisms of DAS on HETs release, and then investigate the immune toxicity of DAS-induced HETs on chicken liver. HETs structures were observed by immunofluorescence staining and mechanisms were investigated by fluorescence microplate and Western blot. The results showed DAS triggered HETs formation which consists of chromatin decorated with citrullinated histone 3 (citH3) and elastase. Glycolysis was confirmed to be involved in this process and the inhibitors of NADPH oxidase, ERK_1/2, p38 MAPK-signaling pathways and glycolysis significantly decreased HETs formation. Moreover, investigation in vivo showed DAS significantly increased HETs formation in serum and DNase I (a standard degradative agent of HETs) significantly decreased the ALT and AST levels and ameliorated DAS-caused inflammatory cell infiltration of liver. In conclusion, this study proves that DAS-induced HETs formation plays an immune toxicity role in chicken liver injury and these results provide a new therapeutic target for DAS-induced liver injury in chickens.

Coordinated Regulation of Mesenchymal Stem Cell Migration by Various Chemotactic Stimuli

Endogenous bone marrow-derived mesenchymal stem cells are mobilized to peripheral blood and injured tissues in response to changes in the expression of various growth factors and cytokines in the injured tissues, including substance P (SP), transforming growth factor-beta (TGF-β), and stromal cell-derived factor-1 (SDF-1). SP, TGF-β, and SDF-1 are all known to induce the migration of bone marrow-derived mesenchymal stem cells (BM-MSCs). However, it is not yet clear how these stimuli influence or interact with each other during BM-MSC mobilization. This study used mouse bone marrow-derived mesenchymal stem cell-like ST2 cells and human BM-MSCs to evaluate whether SP, TGF-β, and SDF-1 mutually regulate their respective effects on the mobilization of BM-MSCs. SP pretreatment of ST2 and BM-MSCs impaired their response to TGF-β while the introduction of SP receptor antagonist restored the mobilization of ST2 and BM-MSCs in response to TGF-β. TGF-β pretreatment did not affect the migration of ST2 and BM-MSCs in response to SP, but downregulated their migration in response to SDF-1. SP pretreatment modulated the activation of TGF-β noncanonical pathways in ST2 cells and BM-MSCs, but not canonical pathways. These results suggest that the migration of mesenchymal stem cells is regulated by complex functional interactions between SP, TGF-β, and SDF-1. Thus, understanding the complex functional interactions of these chemotactic stimuli would contribute to ensuring the development of safe and effective combination treatments for the mobilization of BM-MSCs.