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SerpinA3N attenuates mechanical allodynia after nerve injury. (a,b) Serpina3n mRNA in situ hybridization (a) and western blot analysis (b) of SerpinA3N (55-kDa band) in L3–L4 DRGs from Serpina3n-null mice (Serpina3n−/−) 1 d after SNI. Scale bar, 100 μm. (c) Paw withdrawal thresholds to plantar von Frey application in Serpina3n−/− and WT mice (n = 16 mice per group). (d,e) Western blot analysis of SerpinA3N expression in L3–L4 DRGs (d) and mechanical thresholds (e) in mice receiving intraganglionic injection of AAVs expressing Serpina3n or GFP (n = 8 mice per group). (f,g) Paw withdrawal responses (f) and area under the curve (AUC; g) of mechanical responses (0.04–2 g; expressed in arbitrary units (AU)) in WT mice after i.t. injection of 10 pmol of rSerpinA3N or BSA (control) three times (red arrows) separated by 6-h intervals at 8 d after SNI (n = 12 mice per group). (h–j) Effect of single injections of 3–30 pmol of rSerpinA3N or BSA on mechanical allodynia, represented as responses to 0.16 g (h), thresholds (i) or AUC (0.04–2 g; j) at day 8 after SNI (n = 10–12 mice per dose or vehicle). In c and e, *P < 0.05 compared to basal values and †P < 0.05 compared to the corresponding control. In f–j, *P < 0.05 compared to day 8 after SNI; †P < 0.05 compared to vehicle. In all panels: two-way ANOVA of repeated measures, Tukey's post hoc test. Error bars are means ± s.e.m.
Source publication
Neuropathic pain is a major, intractable clinical problem and its pathophysiology is not well understood. Although recent gene expression profiling studies have enabled the identification of novel targets for pain therapy, classical study designs provide unclear results owing to the differential expression of hundreds of genes across sham and nerve...
Citations
... Additionally, nerve injury-resulting T-cell infiltration in the DRG releases leukocyte elastase (LE)-encoded by Elane, which activates proinflammatory MMP9 and results in the propagation of pain signals in the CNS [25]. The inhibition of leukocyte elastase (LE) is yet another potential target for pain regulation. ...
... The inhibition of leukocyte elastase (LE) is yet another potential target for pain regulation. To determine the extent of T-cell involvement in pain production, T-cells were harvested from wild-type (WT) mice and Elane -/-mice to determine the correlation between LE production and pain [25]. In this study, the researchers found that Elane -/-mice and SerpinA3N-treated mice showed a significant reduction in the development of neuropathic pain [25]. ...
... To determine the extent of T-cell involvement in pain production, T-cells were harvested from wild-type (WT) mice and Elane -/-mice to determine the correlation between LE production and pain [25]. In this study, the researchers found that Elane -/-mice and SerpinA3N-treated mice showed a significant reduction in the development of neuropathic pain [25]. This particular developmental approach is unique from the other developmental approaches discussed in this review, as it utilizes a cDNA vector expressing SerpinA3N [25]. ...
... Human serpina3 (serpin family A member 3), previously known as alpha-1-antichymotrypsin, is a structurally conserved secretory serine protease inhibitor and is homologous to murine serpina3n [7]. Serpina3n/Serpina3 is involved in many biological processes, including complement cascade, apoptosis, proliferation, wound healing, and remodeling of the extracellular matrix by suppressing proteases [8][9][10]. Furthermore, there is growing evidence that Serpina3n/serpina3 plays a critical role in inflammatory responses [11][12][13]. ...
Background/objective
Serpina3n/Serpina3 has been identified to be implicated in inflammatory diseases, but its role in interstitial cystitis/bladder pain syndrome (IC/BPS) remains unknown. Here, we aimed to reveal serpina3n/serpina3 role in IC/BPS in vivo and in vitro.
Methods
The IC/BPS model in mice was induced by intraperitoneal injection of 150 mg/kg of cyclophosphamide (CYP). HE and toluidine blue staining were used for histology assessment. Serpina3n/serpina3 expression in the bladder tissues from IC/BPS patients and mouse models were determined by qPCR, immunohistochemistry and western blotting. XAV-939 treatment was applied to inhibit β-catenin activation. Serpina3 role in modulating the growth and apoptosis of HBlEpCs, a human primary bladder epithelial cell line, was assessed by CCK-8 and flow cytometry assays.
Results
Serpina3n/serpina3 expression was decreased in both human and mice bladder tissues with IC/BPS. Upregulation of serpina3n significantly alleviated CYP-induced bladder injury, with decreased mast cells and pro-inflammatory factor levels, including IL-1β, IL-6, and TNF-α, while increased IL-10 level. In addition, serpina3 overexpression inhibited the apoptosis of HBlEpCs, and increased cell growth. In mechanism, we found that serpina3 overexpression promoted the activation of wnt/β-catenin signaling. And, the inhibition of wnt/β-catenin signaling with XAV-939 abolished serpina3n/serpina3 role in protecting bladder tissues from CYP-induced cystitis, as well as inhibiting HBlEpC apoptosis.
Conclusion
Serpina3n/serpina3 expression was decreased in IC/BPS. Overexpression of serpina3n could alleviate CYP-induced IC/BPS by activating the Wnt/β-catenin signal. This study may provide a new therapeutic strategy for IC/BPS.
... Interestingly, SerpinA3N/SerpinA3 has opposite effects in different diseases. For example, Serpi-nA3N accelerates tissue repair in a diabetic mouse model of delayed wound healing [62], relieves neuronal apoptosis and the impairment of spatial learning and memory function in mice after hippocampal stab injury [29], and attenuates neuropathic pain by inhibiting T cell-derived leukocyte elastase [69]. These findings demonstrate the key role of SerpinA3N in neuroprotection. ...
Impaired activation and regulation of the extinction of inflammatory cells and molecules in injured neuronal tissues are key factors in the development of epilepsy. SerpinA3N is mainly associated with the acute phase response and inflammatory response. In our current study, transcriptomics analysis, proteomics analysis, and Western blotting showed that the expression level of Serpin clade A member 3N (SerpinA3N) is significantly increased in the hippocampus of mice with kainic acid (KA)-induced temporal lobe epilepsy, and this molecule is mainly expressed in astrocytes. Notably, in vivo studies using gain- and loss-of-function approaches revealed that SerpinA3N in astrocytes promoted the release of proinflammatory factors and aggravated seizures. Mechanistically, RNA sequencing and Western blotting showed that SerpinA3N promoted KA-induced neuroinflammation by activating the NF-κB signaling pathway. In addition, co-immunoprecipitation revealed that SerpinA3N interacts with ryanodine receptor type 2 (RYR2) and promotes RYR2 phosphorylation. Overall, our study reveals a novel SerpinA3N-mediated mechanism in seizure-induced neuroinflammation and provides a new target for developing neuroinflammation-based strategies to reduce seizure-induced brain injury.
... Lastly, pain can stem from abnormalities within the nervous system [1]. Among them, one group found an important role for leukocyte elastase and SerpinA 3 N, a member of the serine protease inhibitor superfamily, in the regulation of abnormal neurological pain [2][3][4]. Neutrophil elastase cleavage of protease-activated receptor-2 (PAR 2) at Ala 66 ↓Ser 67 and Ser 67 ↓Val 68 mediates cAMP accumulation and extracellular regulated protein kinases 1/2 (ERK 1/2) activation, and induction of PAR 2 coupled to Gαs leads to PAR 2 and transient receptor potential vanilloid 4 (TRPV 4)-mediated extracellular Ca 2+ influx, and blockade of neutrophil elastase, PAR 2, and ERK 1/2 activity reduces inflammation and pain [5][6][7]. ...
When Poecilobdella manillensis attacks its prey, the prey bleeds profusely but feels little pain. We and other research teams have identified several anticoagulant molecules in the saliva of P. manillensis, but the substance that produces the paralyzing effect in P. manillensis is not known. In this study, we successfully isolated, purified, and identified a serine protease inhibitor containing an antistasin-like domain from the salivary secretions of P. manillensis. This peptide (named poeciguamerin) significantly inhibited elastase activity and slightly inhibited FXIIa and kallikrein activity, but had no effect on FXa, trypsin, or thrombin activity. Furthermore, poeciguamerin exhibited analgesic activity in the foot-licking and tail-withdrawal mouse models and anticoagulant activity in the FeCl3-induced carotid artery thrombosis mouse model. In this study, poeciguamerin was found to be a promising elastase inhibitor with potent analgesic and antithrombotic activity for the inhibition of pain and thrombosis after surgery or in inflammatory conditions.
... Neutrophils release multiple pro-nociceptive enzymes, such as elastase, and inhibition of leuckocyte elastase was found to reduce neuropathic pain in rodents (Bali & Kuner, 2017). Interestingly, it was found that mice that are protected from neuropathic pain express SerpinA3N, a serine protease inhibitor secreted in response to nerve damage by DRG neurons that counteracts the induction of neuropathic pain (Vicuna et al., 2015). ...
It is generally believed that immune activation can elicit pain through production of inflammatory mediators that can activate nociceptive sensory neurons. Emerging evidence suggests that immune activation may also contribute to the resolution of pain by producing distinct pro-resolution/anti-inflammatory mediators. Recent research into the connection between the immune and nervous systems has opened new avenues for immunotherapy in pain management. This review provides an overview of the most utilized forms of immunotherapies (e.g., biologics) and highlight their potential for immune and neuronal modulation in chronic pain. Specifically, we discuss pain-related immunotherapy mechanisms that target inflammatory cytokine pathways, the PD-L1/PD-1 pathway, and the cGAS/STING pathway. This review also highlights cell-based immunotherapies targeting macrophages, T cells, and mesenchymal stromal cells for chronic pain management.
... T Cells have been demonstrated to infiltrate injured nerves, DRG tissue as well as the spinal cord days to weeks after the nerve injury (Hu and McLachlan, 2002;Hu et al., 2007). In neuropathic nerve injury models and using T cell-deficient animals, it seems that activated T Cells promote pain hypersensitivity (Moalem et al., 2004;Cao and DeLeo, 2008;Costigan et al., 2009;Vicuña et al., 2015). In inflammatory pain models, T Cells were also shown to infiltrate after several days where they then persisted in the inflamed tissue (Ghasemlou et al., 2015). ...
The development of novel analgesics for chronic pain in the last 2 decades has proven virtually intractable, typically failing due to lack of efficacy and dose-limiting side effects. Identified through unbiased gene expression profiling experiments in rats and confirmed by human genome-wide association studies, the role of excessive tetrahydrobiopterin (BH4) in chronic pain has been validated by numerous clinical and preclinical studies. BH4 is an essential cofactor for aromatic amino acid hydroxylases, nitric oxide synthases, and alkylglycerol monooxygenase so a lack of BH4 leads to a range of symptoms in the periphery and central nervous system (CNS). An ideal therapeutic goal therefore would be to block excessive BH4 production, while preventing potential BH4 rundown. In this review, we make the case that sepiapterin reductase (SPR) inhibition restricted to the periphery (i.e., excluded from the spinal cord and brain), is an efficacious and safe target to alleviate chronic pain. First, we describe how different cell types that engage in BH4 overproduction and contribute to pain hypersensitivity, are themselves restricted to peripheral tissues and show their blockade is sufficient to alleviate pain. We discuss the likely safety profile of peripherally restricted SPR inhibition based on human genetic data, the biochemical alternate routes of BH4 production in various tissues and species, and the potential pitfalls to predictive translation when using rodents. Finally, we propose and discuss possible formulation and molecular strategies to achieve peripherally restricted, potent SPR inhibition to treat not only chronic pain but other conditions where excessive BH4 has been demonstrated to be pathological.
... The other upregulated gene in the OUM model, Serpina3n, encodes the serine protease inhibitor SerpinA3N, which is expressed in the brain and is associated with apoptosis and wound healing [50]. SerpinA3N has been identified as a pain-inhibiting factor in neuropathic pain models because it suppresses leukocyte elastase activity [51]. In this study, upregulation of these genes was observed in the TG in the OUM model. ...
Severe intraoral pain induces difficulty in eating and speaking, leading to a decline in the quality of life. However, the molecular mechanisms underlying intraoral pain remain unclear. Here, we investigated gene modulation in the trigeminal ganglion and intraoral pain-related behavior in a rat model of acetic acid-induced oral ulcerative mucositis. Oral ulceration was observed on day 2 after acetic acid treatment to the oral mucosa of male Wistar rats, causing spontaneous pain and mechanical allodynia. Deoxyribonucleic acid microarray analysis of trigeminal ganglion tissue indicated that Hamp (a hepcidin gene that regulates cellular iron transport) was the most upregulated gene. In the oral ulcerative mucositis model, the upregulation of Hamp was also induced in the ulcer region but not in the liver, with no increase in hepcidin levels in the plasma and saliva, indicating that hepcidin was produced locally in the ulcer region in the model. Systemic antibiotic pretreatment did not increase the mRNA levels of Hamp in the trigeminal ganglion and ulcer regions. Hepcidin injection into the oral mucosa enhanced neuronal excitability in response to noxious mechanical stimulation of the oral mucosa in trigeminal spinal subnucleus interpolaris/caudalis neurons. These results imply that oral ulcerative mucositis induces oral mucosal pain because of infectious inflammation of the ulcerative area and potentiates Hamp, which represents anti-bacterial and anti-peptidase gene expression in the ulcer region and trigeminal ganglion. The regulation of cellular iron transport by hepcidin is likely involved in oral ulcerative mucositis-induced pain.
... Polarization of resident macrophages in dorsal root ganglia and mitochondrial transfer from infiltrating macrophages to somata can confer sensitization of peripheral sensory neurons (11,12). Similarly, CD3+ T cells have also been described in the resolution pathway of inflammatory pain (13), and pharmacological blockade of T cell-derived leukocyte elastase significantly reduces the magnitude of behavioral hypersensitivity in a rodent model of neuropathic pain (14). Conversely, Na v 1.8+ sensory neurons play a key role in psoriasis and CD8+ T cell responses to viral infection (15). ...
... In the chronic constriction injury model of neuropathic pain, de novo neutrophil infiltration of ipsilateral dorsal root ganglia is observed with direct contact between polymorphonuclear granulocytes and neurons, despite no change in local expression of cytokine-induced neutrophil chemoattractant-1 (17). Moreover, nerve injury in mice leads to T cell and neutrophil infiltration of dorsal root ganglia and development of mechanical hypersensitivity that can be attenuated with inhibition of leukocyte-derived elastase (14,58). We observed de novo infiltration of neutrophils into lumbar DRG in primed mice that could be prevented with antibody depletion of circulating neutrophils (Fig. 3). ...
Fibromyalgia is a debilitating widespread chronic pain syndrome that occurs in 2 to 4% of the population. The prevailing view that fibromyalgia results from central nervous system dysfunction has recently been challenged with data showing changes in peripheral nervous system activity. Using a mouse model of chronic widespread pain through hyperalgesic priming of muscle, we show that neutrophils invade sensory ganglia and confer mechanical hypersensitivity on recipient mice, while adoptive transfer of immunoglobulin, serum, lymphocytes, or monocytes has no effect on pain behavior. Neutrophil depletion abolishes the establishment of chronic widespread pain in mice. Neutrophils from patients with fibromyalgia also confer pain on mice. A link between neutrophil-derived mediators and peripheral nerve sensitization is already established. Our observations suggest approaches for targeting fibromyalgia pain via mechanisms that cause altered neutrophil activity and interactions with sensory neurons.
... Both IL1rn and Saa3 are markers of sterile inflammation, are modulated by gut microbiota [76,77], and are associated with PN in both ob/ob and db/db mouse models [27,[78][79][80]. Mice with Ser-pin3 deficiency exhibit neuropathic pain, which can be reversed by exposure to exogenous Serpin3 [81]. We also identified Adam8, which stimulates axonal extension, as a novel target linking the gut microbiota to sciatic PN [82]. ...
Background
Peripheral neuropathy (PN) is a common complication in obesity, prediabetes, and type 2 diabetes, though its pathogenesis remains incompletely understood. In a murine high-fat diet (HFD) obesity model of PN, dietary reversal (HFD-R) to a low-fat standard diet (SD) restores nerve function and the nerve lipidome to normal. As the gut microbiome represents a potential link between dietary fat intake and nerve health, the current study assessed shifts in microbiome community structure by 16S rRNA profiling during the paradigm of dietary reversal (HFD-R) in various gut niches. Dietary fat content (HFD versus SD) was also correlated to gut flora and metabolic and PN phenotypes. Finally, PN-associated microbial taxa that correlated with the plasma and sciatic nerve lipidome and nerve transcriptome were used to identify lipid species and genes intimately related to PN phenotypes.
Results
Microbiome structure was altered in HFD relative to SD but rapidly reversed with HFD-R. Specific taxa variants correlating positively with metabolic health associated inversely with PN, while specific taxa negatively linked to metabolic health positively associated with PN. In HFD, PN-associated taxa variants, including Lactobacillus, Lachnoclostridium, and Anaerotruncus, also positively correlated with several lipid species, especially elevated plasma sphingomyelins and sciatic nerve triglycerides. Negative correlations were additionally present with other taxa variants. Moreover, relationships that emerged between specific PN-associated taxa variants and the sciatic nerve transcriptome were related to inflammation, lipid metabolism, and antioxidant defense pathways, which are all established in PN pathogenesis.
Conclusions
The current results indicate that microbiome structure is altered with HFD, and that certain taxa variants correlate with metabolic health and PN. Apparent links between PN-associated taxa and certain lipid species and nerve transcriptome-related pathways additionally provide insight into new targets for microbiota and the associated underlying mechanisms of action in PN. Thus, these findings strengthen the possibility of a gut-microbiome-peripheral nervous system signature in PN and support continuing studies focused on defining the connection between the gut microbiome and nerve health to inform mechanistic insight and therapeutic opportunities.
5A96nAvwbUx__NCbnk38-bVideo Abstract
... In addition, the presence of a small number of T lymphocytes in the dura, as well as memory CD4 and CD3 T cells in the subarachnoid space, has been reported (Coles et al., 2015;Schain et al., 2017). However, the relevance of the role of resident DCs and T cells in meningeal neurogenic inflammation in humans remains to be established, although their involvement has been widely shown in pre-clinical models of neuropathic and inflammatory pain (Kashem et al., 2015;Riol-Blanco et al., 2014;Vicuña et al., 2015). ...
The implications of neurogenic inflammation and neuroinflammation in the pathophysiology of migraine have been clearly demonstrated in preclinical migraine models involving several sites relevant in the trigemino-vascular system, including dural vessels and trigeminal endings, the trigeminal ganglion, the trigeminal nucleus caudalis as well as central trigeminal pain processing structures. In this context, a relevant role has been attributed over the years to some sensory and parasympathetic neuropeptides, in particular calcitonin gene neuropeptide, vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide. Several preclinical and clinical lines of evidence also support the implication of the potent vasodilator and messenger molecule nitric oxide in migraine pathophysiology. All these molecules are involved in vasodilation of the intracranial vasculature, as well as in the peripheral and central sensitization of the trigeminal system. At meningeal level, the engagement of some immune cells of innate immunity, including mast-cells and dendritic cells, and their mediators, has been observed in preclinical migraine models of neurogenic inflammation in response to sensory neuropeptides release due to trigemino-vascular system activation. In the context of neuroinflammatory events implicated in migraine pathogenesis, also activated glial cells in the peripheral and central structures processing trigeminal nociceptive signals seem to play a relevant role. Finally, cortical spreading depression, the pathophysiological substrate of migraine aura, has been reported to be associated with inflammatory mechanisms such as pro-inflammatory cytokine upregulation and intracellular signalling. Reactive astrocytosis consequent to cortical spreading depression is linked to an upregulation of these inflammatory markers. The present review summarizes current findings on the roles of immune cells and inflammatory responses in the pathophysiology of migraine and their possible exploitation in the view of innovative disease-modifying strategies.
