Substance P induces M2-type macrophages after spinal cord injury

Sustained Low Serum Substance P Levels in Non-Surviving Septic Patients

Previously, researchers found higher serum substance P (SP) concentrations in survivors of severe sepsis than in non-survivors at the time of severe sepsis diagnosis. The objectives of our current study were to determine whether there is an association between serum SP levels during the first week and sepsis mortality, sepsis severity, serum levels of tumor necrosis factor (TNF)-α and interleukin (IL)-10, and whether serum SP levels during the first week could be used as a biomarker of sepsis mortality. We determined serum concentration of SP, TNF-α, and IL-10 at days 1, 4, and 8. The end-point of the study was mortality at 30 days. We found that non-survivor (n = 104) compared to survivor patients (n = 206) showed lower serum SP levels at days 1, 4, and 8 (p < 0.001). Multiple logistic regression analyses showed an association between 30-day mortality and serum SP levels at days 1, 4, and 8 (p < 0.001) controlling for SOFA score, diabetes mellitus, age, and lactic acid levels. The most interesting findings of our study were that there is an association between serum SP levels during the first week and sepsis mortality, and that serum SP levels during the first week could be used as a biomarker of sepsis mortality.

N-Arachidonoyl Dopamine Modulates Acute Systemic Inflammation via Nonhematopoietic TRPV1

N-Arachidonoyl dopamine (NADA) is an endogenous lipid that potently activates the transient receptor potential vanilloid 1 (TRPV1), which mediates pain and thermosensation. NADA is also an agonist of cannabinoid receptors 1 and 2. We have reported that NADA reduces the activation of cultured human endothelial cells by LPS and TNF-α. Thus far, in vivo studies using NADA have focused on its neurologic and behavioral roles. In this article, we show that NADA potently decreases in vivo systemic inflammatory responses and levels of the coagulation intermediary plasminogen activator inhibitor 1 in three mouse models of inflammation: LPS, bacterial lipopeptide, and polymicrobial intra-abdominal sepsis. We also found that the administration of NADA increases survival in endotoxemic mice. Additionally, NADA reduces blood levels of the neuropeptide calcitonin gene-related peptide but increases the neuropeptide substance P in LPS-treated mice. We demonstrate that the anti-inflammatory effects of NADA are mediated by TRPV1 expressed by nonhematopoietic cells and provide data suggesting that neuronal TRPV1 may mediate NADA's anti-inflammatory effects. These results indicate that NADA has novel TRPV1-dependent anti-inflammatory properties and suggest that the endovanilloid system might be targeted therapeutically in acute inflammation.

Substance P/dexamethasone-encapsulated PLGA scaffold fabricated using supercritical fluid process for calvarial bone regeneration

Poly(lactic-co-glycolic acid) (PLGA) scaffolds encapsulated with substance P (SP) and dexamethasone (Dex) by the supercritical CO₂ foaming method were fabricated to treat calvarial bone. We compared the release profiles of SP and Dex according to the incorporation methods using encapsulation or dipping. Ninety percent of the SP or Dex molecules in the scaffolds prepared by the encapsulating method were released by day 14 or day 6, respectively. In vivo real-time assays for human mesenchymal stem cell (hMSC) tracking were performed to confirm the MSC recruitment abilities of the scaffolds. The results showed that the optical intensity of the SP-encapsulated group was 2.59 times higher than that of the phosphate-buffered saline group and 1.3 times higher than that of the SP-dipping group. Furthermore, we compared the angiogenesis activity of the scaffolds. In the SP-encapsulated group, 72.9  ±  2.6% of the vessels showed matured features by 1 week, and it increased to 82.0  ±  4.6% after 4 weeks. We implanted the scaffolds into rat calvarial defects. After 24 weeks, SP- and Dex-encapsulated scaffolds showed 67.1% and 26.2% higher bone formation than those of the Dex-encapsulated group and SP-encapsulated group, respectively, and they formed 36.1% more bone volume compared with the SP- and Dex-dipped scaffolds. Consequently, the results of this study suggest that SP- and Dex-encapsulated scaffolds made by the supercritical CO₂ foaming method could be a good treatment modality to treat critical bone defects without cell transplantation by recruiting autologous stem cells and forming new bone tissues. Copyright © 2017 John Wiley & Sons, Ltd.

Efficacy of photobiomodulation therapy on masseter thickness and oral health-related quality of life in children with spastic cerebral palsy

The study aimed to evaluate the efficacy of photobiomodulation therapy (PBMT) on bilateral masseter muscle thickness and amplitude of mouth opening in children with spastic cerebral palsy (CP), and the impact on their oral health-related quality of life (OHRQOL). Three groups were included: experimental CP group (EG: n = 26 with oral complaints), positive control CP group (PCG: n = 26 without complaints), and negative control group (NCG: n = 26 without CP). In the EG, the masseter muscles on both sides were irradiated with an infrared low-level Ga-Al-As laser (λ = 808 ± 3 nm, 120 mW) using a 3 J/cm² energy dose per site, with a 20 s exposure time per site (spot area: 4 mm²; irradiance: 3 W/cm²; energy delivery per point: 2.4 J) six times over six consecutive weeks. Masseter thickness, assessed through ultrasonography, and the amplitude of mouth opening were measured in the EG before and after six applications of PBMT and once in the PCG and NCG. The Parental-Caregiver Perception Questionnaire (P-CPQ) was used to evaluate OHRQOL. ANOVA, chi-square, t tests, and multilevel linear regression were used for statistical analysis. In the EG, the study results revealed average increments of 0.77 (0.08) millimeter in masseter thickness (P < 0.05) and 7.39 (0.58) millimeter for mouth opening (P < 0.05) and reduction in all P-CPQ domains (P < 0.001), except for social well-being. The six applications of PBMT increased masseter thickness and mouth opening amplitude and reduced the impact of spastic CP on OHRQOL.

Intravenous Administration of Substance P Attenuates Mechanical Allodynia Following Nerve Injury by Regulating Neuropathic Pain-Related Factors

This study aimed to investigate the analgesic effect of substance P (SP) in an animal model of neuropathic pain. An experimental model of neuropathic pain, the chronic constriction injury (CCI) model, was established using ICR mice. An intravenous (i.v.) injection of SP (1 nmole/kg) was administered to the mice to examine the analgesic effects of systemic SP on neuropathic pain. Behavioral testing and immunostaining was performed following treatment of the CCI model with SP. SP attenuated mechanical allodynia in a time-dependent manner, beginning at 1 h following administration, peaking at 1 day post-injection, and decaying by 3 days post-injection. The second injection of SP also increased the threshold of mechanical allodynia, with the effects peaking on day 1 and decaying by day 3. A reduction in phospho-ERK and glial fibrillary acidic protein (GFAP) accompanied the attenuation of mechanical allodynia. We have shown for the first time that i.v. administration of substance P attenuated mechanical allodynia in the maintenance phase of neuropathic pain using von Frey’s test, and simultaneously reduced levels of phospho-ERK and GFAP, which are representative biochemical markers of neuropathic pain. Importantly, glial cells in the dorsal horn of the spinal cord (L4–L5) of SP-treated CCI mice, expressed the anti-inflammatory cytokine, IL-10, which was not seen in vehicle saline-treated mice. Thus, i.v. administration of substance P may be beneficial for improving the treatment of patients with neuropathic pain, since it decreases the activity of nociceptive factors and increases the expression of anti-nociceptive factors.

Neuropeptides and Microglial Activation in Inflammation, Pain, and Neurodegenerative Diseases

Microglial cells are responsible for immune surveillance within the CNS. They respond to noxious stimuli by releasing inflammatory mediators and mounting an effective inflammatory response. This is followed by release of anti-inflammatory mediators and resolution of the inflammatory response. Alterations to this delicate process may lead to tissue damage, neuroinflammation, and neurodegeneration. Chronic pain, such as inflammatory or neuropathic pain, is accompanied by neuroimmune activation, and the role of glial cells in the initiation and maintenance of chronic pain has been the subject of increasing research over the last two decades. Neuropeptides are small amino acidic molecules with the ability to regulate neuronal activity and thereby affect various functions such as thermoregulation, reproductive behavior, food and water intake, and circadian rhythms. Neuropeptides can also affect inflammatory responses and pain sensitivity by modulating the activity of glial cells. The last decade has witnessed growing interest in the study of microglial activation and its modulation by neuropeptides in the hope of developing new therapeutics for treating neurodegenerative diseases and chronic pain. This review summarizes the current literature on the way in which several neuropeptides modulate microglial activity and response to tissue damage and how this modulation may affect pain sensitivity.

Jisuikang, a Chinese herbal formula, increases neurotrophic factor expression and promotes the recovery of neurological function after spinal cord injury

The Chinese medicine compound, Jisuikang, can promote recovery of neurological function by inhibiting lipid peroxidation, scavenging oxygen free radicals, and effectively improving the local microenvironment after spinal cord injury. However, the mechanism remains unclear. Thus, we established a rat model of acute spinal cord injury using a modified version of Allen's method. Jisuikang (50, 25, and 12.5 g/kg/d) and prednisolone were administered 30 minutes after anesthesia. Basso, Beattie, and Bresnahan locomotor scale scores and the oblique board test showed improved motor function recovery in the prednisone group and moderate-dose Jisuikang group compared with the other groups at 3-7 days post-injury. The rats in the moderate-dose Jisuikang group recovered best at 14 days post-injury. Hematoxylin-eosin staining and transmission electron microscopy showed that the survival rate of neurons in treatment groups increased after 3-7 days of administration. Further, the structure of neurons and glial cells was more distinct, especially in prednisolone and moderate-dose Jisuikang groups. Western blot assay and immunohistochemistry showed that expression of brain-derived neurotrophic factor (BDNF) in injured segments was maintained at a high level after 7-14 days of treatment. In contrast, expression of nerve growth factor (NGF) was down-regulated at 7 days after spinal cord injury. Real-time fluorescence quantitative polymerase chain reaction showed that expression of BDNF and NGF mRNA was induced in injured segments by prednisolone and Jisuikang. At 3-7 days after injury, the effect of prednisolone was greater, while 14 days after injury, the effect of moderate-dose Jisuikang was greater. These results confirm that Jisuikang can upregulate BDNF and NGF expression for a prolonged period after spinal cord injury and promote repair of acute spinal cord injury, with its effect being similar to prednisolone.

Substance P Induces HO-1 Expression in RAW 264.7 Cells Promoting Switch towards M2-Like Macrophages

Substance P (SP) is a neuropeptide that mediates many physiological as well as inflammatory responses. Recently, SP has been implicated in the resolution of inflammation through induction of M2 macrophages phenotype. The shift between M1-like and M2-like, allowing the resolution of inflammatory processes, also takes place by means of hemeoxygenase-1 (HO-1). HO-1 is induced in response to oxidative stress and inflammatory stimuli and modulates the immune response through macrophages polarisation. SP induces HO-1 expression in human periodontal ligament (PDL), the latter potentially plays a role in cytoprotection. We demonstrated that SP promotes M2-like phenotype from resting as well as from M1 macrophages. Indeed, SP triggers the production of interleukine-10 (IL-10), interleukine-4 (IL-4) and arginase-1 (Arg1) without nitric oxide (NO) generation. In addition, SP increases HO-1 expression in a dose- and time-dependent manner. Here we report that SP, without affecting cell viability, significantly reduces the production of pro-inflammatory cytokines and enzymes, such as tumor necrosis factor-alpha (TNF-α), interleukine-6 (IL-6), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and ameliorates migration and phagocytic properties in LPS-stimulated RAW 264.7 cells. M2-like conversion required retention of NF-κB p65 into the cytoplasm and HO-1 induced expression. Silencing of the HO-1 mRNA expression reversed the induction of pro-inflammatory cytokines in RAW 264.7 stimulated by LPS and down-regulated anti-inflammatory hallmarks of M2 phenotype. In conclusion, our data show that SP treatment might be associated with anti-inflammatory effects in LPS-stimulated RAW 264.7 cells by suppressing NF-κB activation and inducing HO-1 expression.

A Comparative Study of Three Different Types of Stem Cells for Treatment of Rat Spinal Cord Injury

Three different sources of human stem cells-bone marrow-derived mesenchymal stem cells (BM-MSCs), neural progenitors (NPs) derived from immortalized spinal fetal cell line (SPC-01), and induced pluripotent stem cells (iPSCs)-were compared in the treatment of a balloon-induced spinal cord compression lesion in rats. One week after lesioning, the rats received either BM-MSCs (intrathecally) or NPs (SPC-01 cells or iPSC-NPs, both intraspinally), or saline. The rats were assessed for their locomotor skills (BBB, flat beam test, and rotarod). Morphometric analyses of spared white and gray matter, axonal sprouting, and glial scar formation, as well as qPCR and Luminex assay, were conducted to detect endogenous gene expression, while inflammatory cytokine levels were performed to evaluate the host tissue response to stem cell therapy. The highest locomotor recovery was observed in iPSC-NP-grafted animals, which also displayed the highest amount of preserved white and gray matter. Grafted iPSC-NPs and SPC-01 cells significantly increased the number of growth-associated protein 43 (GAP43+) axons, reduced astrogliosis, downregulated Casp3 expression, and increased IL-6 and IL-12 levels. hMSCs transiently decreased levels of inflammatory IL-2 and TNF-α. These findings correlate with the short survival of hMSCs, while NPs survived for 2 months and matured slowly into glia- and tissue-specific neuronal precursors. SPC-01 cells differentiated more in astroglial phenotypes with a dense structure of the implant, whereas iPSC-NPs displayed a more neuronal phenotype with a loose structure of the graft. We concluded that the BBB scores of iPSC-NP- and hMSC-injected rats were superior to the SPC-01-treated group. The iPSC-NP treatment of spinal cord injury (SCI) provided the highest recovery of locomotor function due to robust graft survival and its effect on tissue sparing, reduction of glial scarring, and increased axonal sprouting.

Substance-P alleviates dextran sulfate sodium-induced intestinal damage by suppressing inflammation through enrichment of M2 macrophages and regulatory T cells

Intestinal inflammation alters immune responses in the mucosa and destroys colon architecture, leading to serious diseases such as inflammatory bowel disease (IBD). Thus, regulation of inflammation is regarded as the ultimate therapy for intestinal disease. Substance-P (SP) is known to mediate proliferation, migration, and cellular senescence in a variety of cells. SP was found to mobilize stem cells from bone marrow to the site of injury and to suppress inflammatory responses by inducing regulatory T cells (Tregs) and M2 macrophages. In this study, we explored the effects of SP in a dextran sodium sulfate (DSS)-induced intestine damage model. The effects of SP were evaluated by analyzing crypt structures, proliferating cells within the colon, cytokine secretion profiles, and immune cells population in the spleen/mesenteric lymph nodes in vivo. DSS treatment provoked an inflammatory response with loss of crypts in the intestines of experimental mice. This response was associated with high levels of inflammatory cytokines such as TNF-α and IL-17, and low levels of Tregs and M2 macrophages, leading to severely damaged tissue structure. However, SP treatment inhibited inflammatory responses by modulating cytokine production as well as the balance of Tregs/Th 17 cells and the M1/M2 transition in lymphoid organs, leading to accelerated tissue repair. Collectively, our data indicate that SP can promote the regeneration of tissue following damage by DSS treatment, possibly by modulating immune response. Our results propose SP as a candidate therapeutic for intestine-related inflammatory diseases.

Cellular and Molecular Mechanisms Underpinning Macrophage Activation during Remyelination

Remyelination is an example of central nervous system (CNS) regeneration, whereby myelin is restored around demyelinated axons, re-establishing saltatory conduction and trophic/metabolic support. In progressive multiple sclerosis, remyelination is limited or fails altogether which is considered to contribute to axonal damage/loss and consequent disability. Macrophages have critical roles in both CNS damage and regeneration, such as remyelination. This diverse range in functions reflects the ability of macrophages to acquire tissue microenvironment-specific activation states. This activation is dynamically regulated during efficient regeneration, with a switch from pro-inflammatory to inflammation-resolution/pro-regenerative phenotypes. Although, some molecules and pathways have been implicated in the dynamic activation of macrophages, such as NFκB, the cellular and molecular mechanisms underpinning plasticity of macrophage activation are unclear. Identifying mechanisms regulating macrophage activation to pro-regenerative phenotypes may lead to novel therapeutic strategies to promote remyelination in multiple sclerosis.

Effect of substance P on recovery from laser-induced retinal degeneration

Retinal degeneration is caused by neovascularization and persistent inflammation in the retinal pigment epithelium (RPE) and choroid, and causes serious eye disease including age-related macular degeneration (AMD). Thus, inhibiting inflammation and neovascularization may be a primary approach to protect the retina from degeneration. The purpose of this study was to determine whether substance P (SP), which can suppress inflammation and mobilize stem cells, can protect the RPE from degeneration. The effect of SP was evaluated by analyzing systemic inflammation, cell survival, and neovascularization within the argon laser-injured retina of mice. At 1 week postinjury, the SP-treated group had lower tumor necrosis factor-alpha and higher interleukin-10 serum concentrations, and a more intact retinal structure compared to the vehicle-treated group. In mice administered SP repeatedly for 4 weeks, the retinal structure appeared normal and showed sparse neovascularization, whereas the vehicle-treated group showed severe retinal destruction and dense neovascularization. Moreover, the efficacy of SP was identical to that of mesenchymal stem cells that were transplanted into the vitreous after retinal injury. This study highlights the potential for the endogenous neuropeptide SP as a treatment for retinal damage to prevent conditions such as AMD.

Therapeutic effects of neuropeptide substance P coupled with self-assembled peptide nanofibers on the progression of osteoarthritis in a rat model

Osteoarthritis (OA) is a progressively degenerative disease that is accompanied by articular cartilage deterioration, sclerosis of the underlying bone and ultimately joint destruction. Although therapeutic medicine and surgical treatment are done to alleviate the symptoms of OA, it is difficult to restore normal cartilage function. Mesenchymal stem cell (MSC) transplantation is one of the therapeutic trials for treating OA due to its potential, and many researchers have recently reported on the effects of MSCs associated with OA therapy. However, cell transplantation has limitations including low stem cell survival rates, limited stem cell sources and long-term ex vivo culturing. In this study, we evaluated the efficacy of neuropeptide substance P coupled with self-assembled peptide hydrogels in a rat knee model to prevent OA by mobilizing endogenous MSCs to the defect site. To assess the effect of the optimal concentration of SP, varying concentrations of bioactive peptides (substance P (SP) with self-assembled peptide (SAP)) were used to treat OA. OA was induced by unilateral anterior cruciate and medial collateral ligament transection of the knee joints. Forty rats were randomly allocated into 5 groups: SAP-0.5SP (17.5 μg of SP), SAP-SP group (35 μg of SP), SAP-2SP group (70 μg of SP), SAP-SP-MSC group, and control group. At 2 weeks post-surgical induction of OA, each mixture was injected into the joint cavity of the left knee. Histologic examination, immunofluorescence staining, quantitative real time-polymerase chain reaction and micro-computed tomography analysis were done at 6 weeks post-surgical induction. As shown by our results, the SAP-SP hydrogel accelerated tissue regeneration by anti-inflammatory modulation shown by an anti-inflammation test using dot-blot in vitro. Additionally, the treatment of OA in the SAP-SP group showed markedly improved cartilage regeneration through the recruitment of MSCs. Thus, these cells could be infiltrating into the defect site for the regeneration of OA defects. In addition, from the behavioral studies on the rats, the number of rears significantly increased 2 and 4 weeks post-injection in all the groups. Our results show that bioactive peptides may have clinical potential for inhibiting the progression of OA as well as its treatment by recruiting autologous stem cells without cell transplantation.

Alternatively activated microglia and macrophages in the central nervous system

Macrophages are important players in the fight against viral, bacterial, fungal and parasitic infections. From a resting state they may undertake two activation pathways, the classical known as M1, or the alternative known as M2. M1 markers are mostly mediators of pro-inflammatory responses whereas M2 markers emerge for resolution and cleanup. Microglia exerts in the central nervous system (CNS) a function similar to that of macrophages in the periphery. Microglia activation and proliferation occurs in almost any single pathology affecting the CNS. Often microglia activation has been considered detrimental and drugs able to stop microglia activation were considered for the treatment of a variety of diseases. Cumulative evidence shows that microglia may undergo the alternative activation pathway, express M2-type markers and contribute to neuroprotection. This review focuses on details about the role of M2 microglia and in the approaches available for its identification. Approaches to drive the M2 phenotype and data on its potential in CNS diseases are also reviewed.

Understanding the Mysterious M2 Macrophage through Activation Markers and Effector Mechanisms

The alternatively activated or M2 macrophages are immune cells with high phenotypic heterogeneity and are governing functions at the interface of immunity, tissue homeostasis, metabolism, and endocrine signaling. Today the M2 macrophages are identified based on the expression pattern of a set of M2 markers. These markers are transmembrane glycoproteins, scavenger receptors, enzymes, growth factors, hormones, cytokines, and cytokine receptors with diverse and often yet unexplored functions. This review discusses whether these M2 markers can be reliably used to identify M2 macrophages and define their functional subdivisions. Also, it provides an update on the novel signals of the tissue environment and the neuroendocrine system which shape the M2 activation. The possible evolutionary roots of the M2 macrophage functions are also discussed.

Interleukin-33 treatment reduces secondary injury and improves functional recovery after contusion spinal cord injury

Interleukin-33 (IL-33) is a member of the interleukin-1 cytokine family and highly expressed in the naïve mouse brain and spinal cord. Despite the fact that IL-33 is known to be inducible by various inflammatory stimuli, its cellular localization in the central nervous system and role in pathological conditions is controversial. Administration of recombinant IL-33 has been shown to attenuate experimental autoimmune encephalomyelitis progression in one study, yet contradictory reports also exist. Here we investigated for the first time the pattern of IL-33 expression in the contused mouse spinal cord and demonstrated that after spinal cord injury (SCI) IL-33 was up-regulated and exhibited a nuclear localization predominantly in astrocytes. Importantly, we found that treatment with recombinant IL-33 alleviated secondary damage by significantly decreasing tissue loss, demyelination and astrogliosis in the contused mouse spinal cord, resulting in dramatically improved functional recovery. We identified both central and peripheral mechanisms of IL-33 action. In spinal cord, IL-33 treatment reduced the expression of pro-inflammatory tumor necrosis factor-alpha and promoted the activation of anti-inflammatory arginase-1 positive M2 microglia/macrophages, which chronically persisted in the injured spinal cord for up to at least 42 days after the treatment. In addition, IL-33 treatment showed a tendency towards reduced T-cell infiltration into the spinal cord. In the periphery, IL-33 treatment induced a shift towards the Th2 type cytokine profile and reduced the percentage and absolute number of cytotoxic, tumor necrosis factor-alpha expressing CD4+ cells in the spleen. Additionally, IL-33 treatment increased expression of T-regulatory cell marker FoxP3 and reduced expression of M1 marker iNOS in the spleen. Taken together, these results provide the first evidence that IL-33 administration is beneficial after CNS trauma. Treatment with IL33 may offer a novel therapeutic strategy for patients with acute contusion SCI.

Long-term comparative study of Substance-P with methylprednisolone on the development of osteoporosis

Steroids are treated for most inflammatory diseases but cause serious side effects such as diabetes and osteoporosis after their long-term usage. Recently, we identified novel roles of Substance-P (SP) in the suppression of the injury-mediated inflammation and also in stem cell mobilization. In this study, for clinical application of SP as an anti-inflammatory agent, its safety in long-term usage was evaluated with regard to diabetes and osteoporosis. Dexamethasone (DEX) and methylprednisolone (MP) were used as comparative drugs. While DEX-injection for 24 weeks developed severe weight loss, unstable blood glucose, and bone loss, SP-injection did not affect blood glucose and bone mass. MP-injection for 24 weeks also influenced blood glucose and body weight much milder than DEX-injection. After 66 weeks, MP-injection caused unstable blood glucose, alleviation in the age-related increase of body weight, and bone weakness, which was featured by reduction in collagen deposition and trabecular bone volume based on histological and micro CT analysis. However, SP-injection for 66 weeks rather increased collagen deposition, bone volume, and bone density. Therefore, this comparative study suggests that SP, even after long-term usage of effective dose, may not cause side effects such as osteoporosis in comparison to that of DEX and MP and can be developed as an anti-inflammatory agent and/or stem cell mobilizer for long-term treatment.

Microglial and macrophage polarization—new prospects for brain repair

The traditional view of the adult brain as a static organ has changed in the past three decades, with the emergence of evidence that it remains plastic and has some regenerative capacity after injury. In the injured brain, microglia and macrophages clear cellular debris and orchestrate neuronal restorative processes. However, activation of these cells can also hinder CNS repair and expand tissue damage. Polarization of macrophage populations toward different phenotypes at different stages of injury might account for this dual role. This Perspectives article highlights the specific roles of polarized microglial and macrophage populations in CNS repair after acute injury, and argues that therapeutic approaches targeting cerebral inflammation should shift from broad suppression of microglia and macrophages towards subtle adjustment of the balance between their phenotypes. Breakthroughs in the identification of regulatory molecules that control these phenotypic shifts could ultimately accelerate research towards curing brain disorders.

Neuroinflammation and M2 microglia: the good, the bad, and the inflamed

The concept of multiple macrophage activation states is not new. However, extending this idea to resident tissue macrophages, like microglia, has gained increased interest in recent years. Unfortunately, the research on peripheral macrophage polarization does not necessarily translate accurately to their central nervous system (CNS) counterparts. Even though pro- and anti-inflammatory cytokines can polarize microglia to distinct activation states, the specific functions of these states is still an area of intense debate. This review examines the multiple possible activation states microglia can be polarized to. This is followed by a detailed description of microglial polarization and the functional relevance of this process in both acute and chronic CNS disease models described in the literature. Particular attention is given to utilizing M2 microglial polarization as a potential therapeutic option in treating diseases.

A combined ultrasound and histologic approach for analysis of uterine fibroid pseudocapsule thickness

Authors investigated 75 patients with uterine myomas, appraising whether fibroid pseudocapsule (FP) thickness varies depending on fibroid location, by a prospective cohort trial (level of evidence II-2) settled in University-affiliated Hospitals. Uteri were scanned via bidimensional and power Doppler ultrasound (US) to map the fibroids and record the FP thickness, prior to hysterectomy for symptomatic uterine fibroids. After hysterectomy, FP specimens were sampled and analyzed by pathologists. Ultrasound and histology data were matched. Pseudocapsule thickness of 108 fibroids was measured: subserosal fibroids (SSFs), intramural fibroids (IMFs), and fibroids near the endometrial cavity (FEC). The FEC's pseudocapsules were considerably thicker than those of IMF and SSF measured by US and histology (P = .001). A clear cutoff existed between FEC pseudocapsule thickness and all other pseudocapsules, with significant differences observed at 2 mm (P = .001). Similarity between histological and US measurements was observed only with IMF pseudocapsules, whereas FEC or SSF showed significant differences. The pseudocapsule of fibroids is considerably thicker near the endometrial cavity when compared to those of both IMFs and SSFs. Since fibroids closest to the endometrial cavity are the most involved in fertility and infertility and FP is considerably thicker near the endometrial cavity, it is possible to hypothesize an involvement of FP of fibroid near the endometrium since FP contains many neuropeptides and neurotransmitters that are physiologically active, even if these data may take on a broader meaning in a study on a larger number of patients.

NK1 receptor blockade is ineffective in improving outcome following a balloon compression model of spinal cord injury

The neuropeptide substance P (SP) is a well-known mediator of neurogenic inflammation following a variety of CNS disorders. Indeed, inhibition of SP through antagonism of its receptor, the tachykinin NK1 receptor, has been shown to be beneficial following both traumatic brain injury and stroke. Such studies demonstrated that administration of an NK1 receptor antagonist reduced blood-brain-barrier permeability, edema development and improved functional outcome. Furthermore, our recent studies have demonstrated a potential role for SP in mediating neurogenic inflammation following traumatic spinal cord injury (SCI). Accordingly, the present study investigates whether inhibition of SP may similarly play a neuroprotective role following traumatic SCI. A closed balloon compression injury was induced at T10 in New Zealand White rabbits. At 30 minutes post-injury an NK1 receptor antagonist was administered intravenously. Animals were thereafter assessed for blood spinal cord barrier (BSCB) permeability, spinal water content (edema), intrathecal pressure (ITP), and histological and functional outcome from 5 hours to 2 weeks post-SCI. Administration of an NK1 receptor antagonist was not effective in reducing BSCB permeability, edema, ITP, or functional deficits following SCI. We conclude that SP mediated neurogenic inflammation does not seem to play a major role in BSCB disruption, edema development and consequential tissue damage seen in acute traumatic SCI. Rather it is likely that the severe primary insult and subsequent hemorrhage may be the key contributing factors to ongoing SCI injury.

Managing inflammation after spinal cord injury through manipulation of macrophage function

Spinal cord injury (SCI) triggers inflammation with activation of innate immune responses that contribute to secondary injury including oligodendrocyte apoptosis, demyelination, axonal degeneration, and neuronal death. Macrophage activation, accumulation, and persistent inflammation occur in SCI. Macrophages are heterogeneous cells with extensive functional plasticity and have the capacity to switch phenotypes by factors present in the inflammatory microenvironment of the injured spinal cord. This review will discuss the role of different polarized macrophages and the potential effect of macrophage-based therapies for SCI.

Macrophages: supportive cells for tissue repair and regeneration

Macrophages, and more broadly inflammation, have been considered for a long time as bad markers of tissue homeostasis. However, if it is indisputable that macrophages are associated with many diseases in a deleterious way, new roles have emerged, showing beneficial properties of macrophages during tissue repair and regeneration. This discrepancy is likely due to the high plasticity of macrophages, which may exhibit a wide range of phenotypes and functions depending on their environment. Therefore, regardless of their role in immunity, macrophages play a myriad of roles in the maintenance and recovery of tissue homeostasis. They take a major part in the resolution of inflammation. They also exert various effects of parenchymal cells, including stem and progenitor cell, of which they regulate the fate. In the present review, few examples from various tissues are presented to illustrate that, beyond their specific properties in a given tissue, common features have been described that sustain a role of macrophages in the recovery and maintenance of tissue homeostasis.

Neurotensin modulates the migratory and inflammatory response of macrophages under hyperglycemic conditions

Diabetic foot ulcers (DFUs) are characterized by an unsatisfactory inflammatory and migratory response. Skin inflammation involves the participation of many cells and particularly macrophages. Macrophage function can be modulated by neuropeptides; however, little is known regarding the role of neurotensin (NT) as a modulator of macrophages under inflammatory and hyperglycemic conditions. RAW 264.7 cells were maintained at 10/30 mM glucose, stimulated with/without LPS (1 μg/mL), and treated with/without NT(10 nM). The results show that NT did not affect macrophage viability. However, NT reverted the hyperglycemia-induced impair in the migration of macrophages. The expression of IL-6 and IL-1β was significantly increased under 10 mM glucose in the presence of NT, while IL-1β and IL-12 expression significantly decreased under inflammatory and hyperglycemic conditions. More importantly, high glucose modulates NT and NT receptor expression under normal and inflammatory conditions. These results highlight the effect of NT on cell migration, which is strongly impaired under hyperglycemic conditions, as well as its effect in decreasing the proinflammatory status of macrophages under hyperglycemic and inflammatory conditions. These findings provide new insights into the potential therapeutic role of NT in chronic wounds, such as in DFU, characterized by a deficit in the migratory properties of cells and a chronic proinflammatory status.

Expression of substance P, neurokinin-1 receptor and immune markers in the brains of individuals with HIV-associated neuropathology

The tachykinin neuropeptide substance P (SP) has an important signaling role in both the nervous and the immune systems. Two naturally occurring variants of the neurokinin-1 receptor (NK1R) mediate the effects of SP, full-length receptor (NK1R-F) and a truncated form (NK1R-T) that lacks 96 amino acid residues at the C-terminus. We previously reported decreased expression of the NK1R-F in the CNS of HIV-positive individuals in comparison to HIV-negative control subjects. There were no differences in the expression of the NK1R-T in the same groups. In the current study, we quantified the expressions of SP precursor mRNA preprotachykinin (TAC1), NK1R (full and truncated forms), viral load (HIV-gag) and several proinflammatory and immune markers (CD4, CCR5, CXCR4, fractalkine, IL-6, IL-10, CCL2, CCL20 and CD163) in the frontal cortex of autopsied brains from HIV-1-positive individuals with or without HIV-associated neuropathology. The expressions of SP and, to lesser extent, NK1R-F were decreased while the expressions of CXCR4, CCR5 and CCL2 were increased in CNS of individuals with HIV-associated neuropathology. There was no change in HIV loads associated with neuropathology; however, we found a positive correlation between viral loads and the expression of haptoglobin-hemoglobin scavenger receptor CD163. An analysis of CSF from corresponding samples demonstrated an increase in proinflammatory markers (CCL2 MIP-1α and MIP-1β) associated with neuropathology. Although our data confirm the overall inflammatory nature of HIV-associated neuropathology, we observed a decrease in the expression of SP and NK1R-F, which is also associated with other forms of neuroinflammation.