Role of CXCR2 and TRPV1 in functional, inflammatory and behavioural changes in the rat model of cyclophosphamide-induced haemorrhagic cystitis

Mechanisms underlying dose-limiting toxicities of conventional chemotherapeutic agents

Dose-limiting toxicities (DLTs) are severe adverse effects that define the maximum tolerated dose of a cancer drug. In addition to the specific mechanisms of each drug, common contributing factors include inflammation, apoptosis, ion imbalances, and tissue-specific enzyme deficiencies. Among various DLTs are bleomycin-induced pulmonary fibrosis, doxorubicin-induced cardiomyopathy, cisplatin-induced nephrotoxicity, methotrexate-induced hepatotoxicity, vincristine-induced neurotoxicity, paclitaxel-induced peripheral neuropathy, and irinotecan, which elicits severe diarrhea. Currently, specific treatments beyond dose reduction are lacking for most toxicities. Further research on cellular and molecular pathways is imperative to improve their management. This review synthesizes preclinical and clinical data on the pharmacological mechanisms underlying DLTs and explores possible treatment approaches. A comprehensive perspective reveals knowledge gaps and emphasizes the need for future studies to develop more targeted strategies for mitigating these dose-dependent adverse effects. This could allow the safer administration of fully efficacious doses to maximize patient survival.

Chemokine receptor CXCR2 in primary sensory neurons of trigeminal ganglion mediates orofacial itch

The CXCR2 chemokine receptor is known to have a significant impact on the initiation and control of inflammatory processes. However, its specific involvement in the sensation of itch is not yet fully understood. In this study, we aimed to elucidate the function of CXCR2 in the trigeminal ganglion (TG) by utilizing orofacial itch models induced by incision, chloroquine (CQ), and histamine. Our results revealed a significant up-regulation of CXCR2 mRNA and protein expressions in the primary sensory neurons of TG in response to itch stimuli. The CXCR2 inhibitor SB225002 resulted in notable decrease in CXCR2 protein expression and reduction in scratch behaviors. Distal infraorbital nerve (DION) microinjection of a specific shRNA virus inhibited CXCR2 expression in TG neurons and reversed itch behaviors. Additionally, the administration of the PI3K inhibitor LY294002 resulted in a decrease in the expressions of p-Akt, Akt, and CXCR2 in TG neurons, thereby mitigating pruritic behaviors. Collectively, we report that CXCR2 in the primary sensory neurons of trigeminal ganglion contributes to orofacial itch through the PI3K/Akt signaling pathway. These observations highlight the potential of molecules involved in the regulation of CXCR2 as viable therapeutic targets for the treatment of itch.

[8] and [10]-Gingerol reduces urothelial damage in ifosfamide-induced hemorrhagic cystitis via JAK/STAT/FOXO signaling pathway via IL-10

Acrolein is the main toxic metabolite of ifosfamide (IFO) that causes urothelial damage by oxidative stress and inflammation. Here, we investigate the molecular mechanism of action of gingerols, Zingiber officinale bioactive molecules, as an alternative treatment for ifosfamide-induced hemorrhagic cystitis. Female Swiss mice were randomly divided into 5 groups: control; IFO; IFO + Mesna; and IFO + [8]- or [10]-gingerol. Mesna (80 mg/kg, i.p.) was given 5 min before, 4 and 8 h after IFO (400mg/kg, i.p.). Gingerols (25 mg/kg, p.o.) were given 1 h before and 4 and 8 h after IFO. Animals were euthanized 12 h after IFO injection. Bladders were submitted to macroscopic and histological evaluation. Oxidative stress and inflammation were assessed by malondialdehyde (MDA) or myeloperoxidase assays, respectively. mRNA gene expression was performed to evaluate mesna and gingerols mechanisms of action. Mesna was able to protect bladder tissue by activating NF-κB and NrF2 pathways. However, we demonstrated that gingerols acted as an antioxidant and anti-inflammatory agent stimulating the expression of IL-10, which intracellularly activates JAK/STAT/FOXO signaling pathway.

Cyclophosphamide induced intestinal injury is alleviated by blocking the TLR9/caspase3/GSDME mediated intestinal epithelium pyroptosis

OBJECTIVES

Cyclophosphamide (CYC) was commonly used to treat autoimmune disorders, and it could also cause side effects such as intestinal damage. This study aimed to explore the mechanism of CYC-induced intestinal cytotoxicity and provide evidence for protecting from intestinal damage by blocking TLR9/caspase3/GSDME mediated pyroptosis.

METHODS

Intestinal epithelial cells (IEC-6) were treated with 4-hydroxycyclophosphamide (4HC), a key active metabolite of CYC. The pyroptotic rate of IEC-6 cells was detected by Annexin V/PI-Flow cytometry, microscopy imaging, and PI staining. The expression and activation of TLR9, caspase3 and GSDME in IEC-6 cells were detected by western blot and immunofluorescence staining. In addition, hydroxychloroquine (HCQ) and ODN2088 were used to inhibit TLR9 to investigate the role of TLR9 on caspase3/GSDME-mediated pyroptosis. Finally, mice lacking Gsdme or TLR9 or pretreating with HCQ were injected intraperitoneally with CYC, and the incidence and severity of intestinal damage were assessed.

RESULTS

CYC induced lytic cell death in IEC-6 cells and increased the expression of TLR9, activated caspase3, and GSDME-N. Besides, both ODN2088 and HCQ could inhibit CYC-induced pyroptosis in IEC-6 cells. In vivo, CYC-induced intestinal injury was characterized by a large amount of intestinal villi abscission and structural disordered. Gsdme or TLR9 deficiency, or pretreatment of HCQ effectively attenuated intestinal damage in CYC-induced model mice.

CONCLUSIONS

These results indicate an alternative mechanism for CYC-induced intestinal damage, which actives TLR9/caspase3/GSDME signaling pathway, leading to pyroptosis of intestinal epithelial cells. And targeting pyroptosis might be a potential therapeutic approach for CYC-induced intestinal damage.

Chemokine CCL7 mediates trigeminal neuropathic pain via CCR2/CCR3-ERK pathway in the trigeminal ganglion of mice

BACKGROUND

Chemokine-mediated neuroinflammation plays an important role in the pathogenesis of neuropathic pain. The chemokine CC motif ligand 7 (CCL7) and its receptor CCR2 have been reported to contribute to neuropathic pain via astrocyte-microglial interaction in the spinal cord. Whether CCL7 in the trigeminal ganglion (TG) involves in trigeminal neuropathic pain and the involved mechanism remain largely unknown.

METHODS

The partial infraorbital nerve transection (pIONT) was used to induce trigeminal neuropathic pain in mice. The expression of Ccl7, Ccr1, Ccr2, and Ccr3 was examined by real-time quantitative polymerase chain reaction. The distribution of CCL7, CCR2, and CCR3 was detected by immunofluorescence double-staining. The activation of extracellular signal-regulated kinase (ERK) was examined by Western blot and immunofluorescence. The effect of CCL7 on neuronal excitability was tested by whole-cell patch clamp recording. The effect of selective antagonists for CCR1, CCR2, and CCR3 on pain hypersensitivity was checked by behavioral testing.

RESULTS

Ccl7 was persistently increased in neurons of TG after pIONT, and specific inhibition of CCL7 in the TG effectively relieved pIONT-induced orofacial mechanical allodynia. Intra-TG injection of recombinant CCL7 induced mechanical allodynia and increased the phosphorylation of ERK in the TG. Incubation of CCL7 with TG neurons also dose-dependently enhanced the neuronal excitability. Furthermore, pIONT increased the expression of CCL7 receptors Ccr1, Ccr2, and Ccr3. The intra-TG injection of the specific antagonist of CCR2 or CCR3 but not of CCR1 alleviated pIONT-induced orofacial mechanical allodynia and reduced ERK activation. Immunostaining showed that CCR2 and CCR3 are expressed in TG neurons, and CCL7-induced hyperexcitability of TG neurons was decreased by antagonists of CCR2 or CCR3.

CONCLUSION

CCL7 activates ERK in TG neurons via CCR2 and CCR3 to enhance neuronal excitability, which contributes to the maintenance of trigeminal neuropathic pain. CCL7-CCR2/CCR3-ERK pathway may be potential targets for treating trigeminal neuropathic pain.

CXCR2 Is Essential for Radiation-Induced Intestinal Injury by Initiating Neutrophil Infiltration

Neutrophils, known as an important part of the immune system, are the most abundant leukocyte population in peripheral blood, but excessive recruitment will lead to tissue/organ injury. RNA sequencing showed that ionizing radiation significantly increased the expression of characteristic genes of neutrophils in intestinal tissues compared with liver and lung tissues. By clearing neutrophils with an anti-Ly6G antibody, we found that neutrophil infiltration is critical for irradiation-induced intestinal injury. CXCR2 is a G-protein-coupled receptor that mediates the migration of neutrophils by combining with its ligands. Compared with observations in liver and lung tissues, we found that CXCR2 and its ligands, including CXCL1, CXCL2, CXCL3, and CXCL5, were all significantly upregulated in irradiated intestinal tissues. Further studies showed that SB225002, an inhibitor of CXCR2, could effectively inhibit the chemotaxis of neutrophils and tissue damage mediated by the CXCL-CXCR2 signalling pathway.

The Nitrogen Mustards

The nitrogen mustards are powerful cytotoxic and lymphoablative agents and have been used for more than 60 years. They are employed in the treatment of cancers, sarcomas, and hematologic malignancies. Cyclophosphamide, the most versatile of the nitrogen mustards, also has a place in stem cell transplantation and the therapy of autoimmune diseases. Adverse effects caused by the nitrogen mustards on the central nervous system, kidney, heart, bladder, and gonads remain important issues. Advances in analytical techniques have facilitated the investigation of the pharmacokinetics of the nitrogen mustards, especially the oxazaphosphorines, which are prodrugs requiring metabolic activation. Enzymes involved in the metabolism of cyclophosphamide and ifosfamide are very polymorphic, but a greater understanding of the pharmacogenomic influences on their activity has not yet translated into a personalized medicine approach. In addition to damaging DNA, the nitrogen mustards can act through other mechanisms, such as antiangiogenesis and immunomodulation. The immunomodulatory properties of cyclophosphamide are an area of current exploration. In particular, cyclophosphamide decreases the number and activity of regulatory T cells, and the interaction between cyclophosphamide and the intestinal microbiome is now recognized as an important factor. New derivatives of the nitrogen mustards continue to be assessed. Oxazaphosphorine analogs have been synthesized in attempts to both improve efficacy and reduce toxicity, with varying degrees of success. Combinations of the nitrogen mustards with monoclonal antibodies and small-molecule targeted agents are being evaluated. SIGNIFICANCE STATEMENT: The nitrogen mustards are important, well-established therapeutic agents that are used to treat a variety of diseases. Their role is continuing to evolve.

The Isopropyl Gallate Counteracts Cyclophosphamide-Induced Hemorrhagic Cystitis in Mice

Simple Summary

Ifosfamide (IFOS) is an antineoplastic drug used to treat various cancers. Hemorrhagic cystitis (HC) is the main adverse effect related to the use of IFOS. Acrolein, a metabolite of IFOS, is the main molecule responsible for this side-effect, resulting in increased oxidative stress and production of inflammatory mediators, which culminate in the degradation of bladder tissue. In clinical practice, mesna is used to reduce the incidence of HC. However, this drug presents some dose-dependent side effects. Isopropyl gallate (IPG), a gallic acid-derived compound, is promising for the development of new anti-inflammatory agents. In the present study, the effects of oral administration of IPG against IFOS-induced hemorrhagic cystitis in mice were investigated. Interestingly pretreatment of IPG was able to reduce IFOS-induced bladder damage evidenced by a decrease of inflammatory parameters and improvement in histology and antioxidants of the urinary bladder. Furthermore, IPG significantly decreased the expression levels of inflammatory biomarkers in the bladder tissue. These preliminary findings suggest that IPG represents a promising adjuvant therapy for protecting against IFOS-induced urotoxicity.

Abstract

Hemorrhagic cystitis is the main adverse effect associated with the clinical use of oxazaphosphorine, resulting in increased oxidative stress and proinflammatory cytokines, which culminate in injury of the bladder tissue. The aim of this study was to evaluate the protective effect of isopropyl gallate (IPG) against ifosfamide (IFOS)-induced hemorrhagic cystitis in mice. The induction of the hemorrhagic cystitis model was carried out using a single dose of IFOS (400 mg/kg, i.p.) four hours after oral pretreatment with IPG (6.25, 12.5, 25, and 50 mg/kg) or saline (vehicle). Mesna (positive control; 80 mg/kg, i.p.) was administered four hours before and eight hours after induction of cystitis. In the present study, IPG 25 mg/kg significantly decreased edema and hemorrhage, with a reduction of the bladder wet weight (36.86%), hemoglobin content (54.55%), and peritoneal vascular permeability (42.94%) in urinary bladders of mice. Interestingly, IPG increased SOD activity (89.27%) and reduced MDA levels (35.53%), as well as displayed anti-inflammatory activity by decreasing TNF-α (88.77%), IL-1β (62.87%), and C-reactive protein (56.41%) levels. Our findings demonstrate that IPG has a substantial protective role against IFOS-induced hemorrhagic cystitis in mice by enhancing antioxidant activity and proinflammatory mechanisms. Thus, IPG represents a promising co-adjuvant agent in oxazaphosphorine-based chemotherapy treatments.

Inflammation-Independent Antinociceptive Effects of DF2755A, a CXCR1/2 Selective Inhibitor: A New Potential Therapeutic Treatment for Peripheral Neuropathy Associated to Non-Ulcerative Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis (IC)/bladder pain syndrome (BPS) is a chronic bladder disease of unknown etiology characterized by urinary frequency and episodic and chronic pain. Analgesic treatments for IC/BPS are limited, especially for patients with non-Hunner (non-ulcerative) type IC who usually have poor overall outcomes. Here, we demonstrate that oral treatment with DF2755A, a potent and selective inhibitor of chemokine receptors CXCR1/2, can prevent and reverse peripheral neuropathy associated to non-Hunner IC/BPS by directly inhibiting chemokine-induced excitation of sensory neurons. We tested DF2755A antinociceptive effects in a cyclophosphamide (CYP)-induced non-ulcerative IC rat model characterized by severe peripheral neuropathy in the absence of bladder inflammatory infiltrate, urothelial hyperplasia, and hemorrhage. Treatment with DF2755A prevented the onset of peripheral neuropathy and reversed its development in CYP-induced IC rats, showing a strong and long-lasting anti-hyperalgesic effect. Ex vivo and in vitro studies showed that DF2755A treatment strongly inhibited the expression of CXCR2 agonists, CXCL1/KC, and CXCL5 and of transient receptor potential vanilloid 1 (TRPV1) compared to vehicle, suggesting that its effects can be due to the inhibition of the nociceptive signaling passing through the CXCL1/CXCR1-2 axis and TRPV1. In conclusion, our results highlight the key pathophysiological role played by the CXCL1/CXCR1-2 axis and TRPV1 in the onset and development of peripheral neuropathy in non-Hunner IC and propose DF2755A as a potential therapeutic approach for the treatment of not only inflammatory painful conditions but also neuropathic ones and in particular non-Hunner IC/BPS.

Activation of GPR18 by Resolvin D2 Relieves Pain and Improves Bladder Function in Cyclophosphamide-Induced Cystitis Through Inhibiting TRPV1

Purpose

Hyperalgesia and bladder overactivity are two main symptoms of interstitial cystitis/bladder pain syndrome (IC/BPS). Cannabinoid receptors participate in the modulation of pain and bladder function. GPR18, a member of the cannabinoid receptor family, also participates in the regulation of pain and bladder function, but its underlying mechanisms are unknown. In this work, we sought to study the role of GPR18 in IC/BPS.

Methods

A rat model of IC/BPS was established with cyclophosphamide (CYP). Paw withdrawal threshold (PWT) measurement and cystometry were used to evaluate pain and bladder function, respectively. RT-PCR, Western blotting and immunofluorescence were used to assess the expression and distribution of GPR18. The role of GPR18 in pain and bladder function was studied by intrathecal injection of resolvin D2 (RvD2, a GPR18 agonist) and O-1918 (a GPR18 antagonist). Calcium imaging was used to study the relationship between GPR18 and TRPV1.

Results

A rat model of IC/BPS, which exhibited a decreased PWT and micturition interval, was successfully established with CYP. The mRNA and protein expression of GPR18 was reduced in the bladder and dorsal root ganglia (DRG) in rats with CYP-induced cystitis. Intrathecal injection of RvD2 increased the PWT and micturition interval. However, O-1918 blocked the therapeutic effect of RvD2. GPR18 was present in bladder afferent nerves and colocalized with TRPV1 in DRG, and RvD2 decreased capsaicin-induced calcium influx in DRG.

Conclusion

Activation of GPR18 by RvD2 alleviated hyperalgesia and improved bladder function, possibly by inhibiting TRPV1 in rats with CYP-induced cystitis.

The Role of PIEZO1 in Urinary Bladder Function and Dysfunction in a Rodent Model of Cyclophosphamide-Induced Cystitis

In the urinary bladder, mechanosensitive ion channels (MSCs) underlie the transduction of bladder stretch into sensory signals that are relayed to the PNS and CNS. PIEZO1 is a recently identified MSC that is Ca²⁺ permeable and is widely expressed throughout the lower urinary tract. Recent research indicates that PIEZO1 is activated by mechanical stretch or by pharmacological agonism via Yoda1. Aberrant activation of PIEZO1 has been suggested to play a role in clinical bladder pathologies like partial bladder outlet obstruction and interstitial cystitis/bladder pain syndrome (IC/BPS). In the present study, we show that intravesical instillation of Yoda1 in female Wistar rats leads to increased voiding frequency for up to 16 hours after administration compared to vehicle treatment. In a cyclophosphamide (CYP) model of cystitis, we found that the gene expression of several candidate MSCs (Trpv1, Trpv4, Piezo1, and Piezo2) were all upregulated in the urothelium and detrusor following chronic CYP-induced cystitis, but not acute CYP-induced cystitis. Functionally with this model, we show that Ca²⁺ activity is increased in urothelial cells following PIEZO1 activation via Yoda1 in acute and intermediate CYP treatment, but not in naïve (no CYP) nor chronic CYP treatment. Lastly, we show that activation of PIEZO1 may contribute to pathological bladder dysfunction through the downregulation of several tight junction genes in the urothelium including claudin-1, claudin-8, and zona occludens-1. Together, these data suggest that PIEZO1 activation plays a role in dysfunctional voiding behavior and may be a future, clinical target for the treatment of pathologies like IC/BPS.

Intravesical CD74 and CXCR4, macrophage migration inhibitory factor (MIF) receptors, mediate bladder pain

Background

Activation of intravesical protease activated receptor 4 (PAR4) leads to release of urothelial macrophage migration inhibitory factor (MIF). MIF then binds to urothelial MIF receptors to release urothelial high mobility group box-1 (HMGB1) and elicit bladder hyperalgesia. Since MIF binds to multiple receptors, we investigated the contribution of individual urothelial MIF receptors to PAR4-induced HMGB1 release in vivo and in vitro and bladder pain in vivo.

Methodology/Principal findings

We tested the effect of intravesical pre-treatment with individual MIF or MIF receptor (CD74, CXCR4, CXCR2) antagonists on PAR4-induced HMGB1 release in vivo (female C57/BL6 mice) and in vitro (primary human urothelial cells) and on PAR4-induced bladder hyperalgesia in vivo (mice). In mice, PAR4 induced HMGB1 release and bladder hyperalgesia through activation of intravesical MIF receptors, CD74 and CXCR4. CXCR2 was not involved in these effects. In primary urothelial cells, PAR4-induced HMGB1 release through activation of CD74 receptors. Micturition parameters in mice were not changed by any of the treatments.

Conclusions/Significance

Urothelial MIF receptors CD74 and CXCR4 mediate bladder pain through release of urothelial HMGB1. This mechanism may set up persistent pain loops in the bladder and warrants further investigation. Urothelial CD74 and CXCR4 may provide novel targets for interrupting bladder pain.

Modulation of autophagy and transient receptor potential vanilloid 4 channels by montelukast in a rat model of hemorrhagic cystitis

AIMS

Hemorrhagic cystitis (HC) is a major urotoxic complication of cyclophosphamide (CPA) therapy. This study investigated the uroprotective effect of montelukast on CPA-induced HC, compared to the efficacy of 2-mercaptoethane sulfonate sodium (MESNA).

MAIN METHODS

Male albino rats were pretreated with MESNA (40 mg/kg/day, IP) or montelukast (10 mg/kg/day, orally) for three days then received a single dose of CPA (200 mg/kg, IP), 1 h after the last dose, and compared to CPA-treated rats receiving drug vehicle. Age-matched rats were used as controls. Bladders of rats were assessed biochemically, macroscopically and microscopically by light and electron microscope 24 h later.

KEY FINDINGS

CPA injection contributed to increased bladder weight, urothelial ulceration, vascular congestion, hemorrhage, increased collagen deposition and mast cell infiltration, compared to control rats. Montelukast preconditioning suppressed mast cell infiltration and inflammatory mediators to greater extent than MESNA. Also, montelukast enhanced autophagosomes formation in detrusor myocytes and up-regulated the autophagy-related proteins (beclin-1 & LC3-II), likely through inhibition of phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway. Montelukast preconditioning offset the up-regulation of transient receptor potential vanilloid 4 (TRPV4) in urothelial tissue of CPA-treated rats, to greater extent than MESNA.

SIGNIFICANCE

These results demonstrate the uroprotective effect of montelukast on CPA-induced HC, which appears to be more superior to MESNA. These findings suggest that montelukast can emerge as a novel strategy to protect against CPA-induced urotoxicity.

Immunohistochemistry as a paramount tool in research of normal urothelium, bladder cancer and bladder pain syndrome

The urothelium, an epithelium of the urinary bladder, primarily functions as blood-urine permeability barrier. The urothelium has a very slow turnover under normal conditions but is capable of extremely fast response to injury. During regeneration urothelium either restores normal function or undergoes altered differentiation pathways, the latter being the cause of several bladder diseases. In this review, we describe the structure of the apical plasma membrane that enables barrier function, the role of urothelium specific proteins uroplakins and the machinery for polarized membrane transports in terminally differentiated superficial umbrella cells. We address key markers, such as keratins, cancer stem cell markers, retinoic acid signalling pathway proteins and transient receptor potential channels and purinergic receptors that drive normal and altered differentiation in bladder cancer and bladder pain syndrome. Finally, we discuss uncertainties regarding research, diagnosis and treatment of bladder pain syndrome. Throughout the review, we emphasise the contribution of immunohistochemistry in advancing our understanding of processes in normal and diseased bladder as well as the most promising possibilities for improved bladder cancer and bladder pain syndrome management.

Transient receptor potential channels in sensory mechanisms of the lower urinary tract

Disruptions to sensory pathways in the lower urinary tract commonly occur and can give rise to lower urinary tract symptoms (LUTS). The unmet clinical need for treatment of LUTS has stimulated research into the molecular mechanisms that underlie neuronal control of the bladder and transient receptor potential (TRP) channels have emerged as key regulators of the sensory processes that regulate bladder function. TRP channels function as molecular sensors in urothelial cells and afferent nerve fibres and can be considered the origin of bladder sensations. TRP channels in the lower urinary tract contribute to the generation of normal and abnormal bladder sensations through a variety of mechanisms, and have demonstrated potential as targets for the treatment of LUTS in functional disorders of the lower urinary tract.

Modulation of Sensory Nerve Function by Insulin: Possible Relevance to Pain, Inflammation and Axon Growth

Insulin, besides its pivotal role in energy metabolism, may also modulate neuronal processes through acting on insulin receptors (InsRs) expressed by neurons of both the central and the peripheral nervous system. Recently, the distribution and functional significance of InsRs localized on a subset of multifunctional primary sensory neurons (PSNs) have been revealed. Systematic investigations into the cellular electrophysiology, neurochemistry and morphological traits of InsR-expressing PSNs indicated complex functional interactions among specific ion channels, proteins and neuropeptides localized in these neurons. Quantitative immunohistochemical studies have revealed disparate localization of the InsRs in somatic and visceral PSNs with a dominance of InsR-positive neurons innervating visceral organs. These findings suggested that visceral spinal PSNs involved in nociceptive and inflammatory processes are more prone to the modulatory effects of insulin than somatic PSNs. Co-localization of the InsR and transient receptor potential vanilloid 1 (TRPV1) receptor with vasoactive neuropeptides calcitonin gene-related peptide and substance P bears of crucial importance in the pathogenesis of inflammatory pathologies affecting visceral organs, such as the pancreas and the urinary bladder. Recent studies have also revealed significant novel aspects of the neurotrophic propensities of insulin with respect to axonal growth, development and regeneration.

Tacrolimus increases the expression level of the chemokine receptor CXCR2 to promote renal fibrosis progression

Tacrolimus is one of the most used and effective immunosuppressive agents currently available in the clinic; however, its use is limited by nephrotoxicity, which is the main secondary effect of this drug. The mechanisms underlying tacrolimus-induced nephrotoxicity remain unknown. The present study aimed to investigate the mechanism underlying tacrolimus-induced nephrotoxicity and to identify novel potential targets. Masson staining, Sirius red staining and periodic acid-silver methenamine staining were used to observe kidney pathological changes. Immunohistochemical and immunofluorescent analyses were performed to examine the expression levels of vimentin, E-cadherin and α-smooth muscle actin (α-SMA). Transcriptomics and bioinformatics analyses were performed to investigate the nephrotoxicity mechanism induced by tacrolimus using RNA-sequencing, differentially expressed genes identification and annotation, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The present results demonstrated that compared with the normal control group, the tacrolimus nephrotoxicity group exhibited severe renal fibrosis (P<0.05), upregulated vimentin (P<0.01), downregulated E-cadherin (P<0.05) and upregulated α-SMA (P<0.01). Transcriptomics and bioinformatics analyses identified the pathway 'cytokine-cytokine receptor interaction' as the most significantly enriched (P<0.05). Moreover, KEGG pathway enrichment analysis identified that tacrolimus increased the expression levels of chemokine (C-X-C) motif ligand (CXCL)1, CXCL2 and CXCL3 and the chemokine receptor C-X-C chemokine receptor type 2 (CXCR2). Collectively, the present study suggested that tacrolimus increases the level of chemokine receptor CXCR2 to promote renal fibrosis progression, which is one of the potential mechanisms underlying tacrolimus-induced nephrotoxicity.

IPSE, a urogenital parasite-derived immunomodulatory protein, ameliorates ifosfamide-induced hemorrhagic cystitis through downregulation of pro-inflammatory pathways

Ifosfamide and other oxazaphosphorines can result in hemorrhagic cystitis, a constellation of complications caused by acrolein metabolites. We previously showed that a single dose of IPSE (Interleukin-4-inducing principle from Schistosoma eggs), a schistosome-derived host modulatory protein, can ameliorate ifosfamide-related cystitis; however, the mechanisms underlying this urotoxicity and its prevention are not fully understood. To provide insights into IPSE’s protective mechanism, we undertook transcriptional profiling of bladders from ifosfamide-treated mice, with or without pretreatment with IPSE or IPSE-NLS (a mutant of IPSE lacking nuclear localization sequence). Ifosfamide treatment upregulated a range of proinflammatory genes. The IL-1β-TNFα-IL-6 proinflammatory cascade via NFκB and STAT3 pathways was identified as the key driver of inflammation. The NRF2-mediated oxidative stress response pathway, which regulates heme homoeostasis and expression of antioxidant enzymes, was highly activated. Anti-inflammatory cascades, namely Wnt, Hedgehog and PPAR pathways, were downregulated. IPSE drove significant downregulation of major proinflammatory pathways including the IL-1β-TNFα-IL-6 pathways, interferon signaling, and reduction in oxidative stress. IPSE-NLS reduced inflammation but not oxidative stress. Taken together, we have identified signatures of acute-phase inflammation and oxidative stress in ifosfamide-injured bladder, which are reversed by pretreatment with IPSE. This work revealed several pathways that could be therapeutically targeted to prevent ifosfamide-induced hemorrhagic cystitis.

1,3-Dibromo-1,1-difluoro-2-propanone as a Useful Synthon for a Chemoselective Preparation of 4-Bromodifluoromethyl Thiazoles

We report herein a synthetic protocol for the preparation of 1,3-dibromo-1,1-difluoro-2-propanone, a new synthon used for the first time in a reaction with aromatic amines and sodium thiocyanate, leading to thiazoles which are useful candidates in drug discovery programs. The new synthon allows to introduce a bromodifluoromethyl group at the C4 of the thiazole, and it is amenable of further transformation such as the Br/F exchange useful in radiopharmaceutics. Application of the strategy to the preparation of a precursor of the biologically relevant DF2755Y is also reported.

Neonatal Bladder Irritation Is Associated With Vanilloid Receptor TRPV1 Expression in Adult Rats

PURPOSE

To evaluate whether mild chemical irritation of the bladder in neonatal rats is associated with persistent vanilloid receptor transient receptor potential vanilloid subfamily 1 (TRPV1) activity in adult rats.

METHODS

Female Sprague-Dawley rats were used. Ten-day-old rat pups underwent bladder sensitization via intravesical infusion of 0.2% acetic acid in saline with or without prior bladder desensitization with capsaicin. After 8 weeks, 3 groups of rats (control [group 1], bladder sensitization [group 2], and bladder desensitization [group 3]) underwent cystometry. Inflammation of bladder tissue and the expression of TRPV1 in bladder tissue and dorsal root ganglia (DRG) were also evaluated.

RESULTS

The bladder sensitization group showed more frequent voiding contractions. TRPV1 expression in adult bladder tissue was elevated in group 2. TRPV1 mRNA levels in the bladder and DRG were significantly higher in group 2 than in group 1. Moreover, group 2 had significantly more DRG neurons (identified by uptake of the retrograde label Fast Blue) that exhibited TRPV1 immunoreactivity.

CONCLUSION

We found a significant association between neonatal bladder sensitization and persistent TRPV1 activity in adult rats. This is the first study to focus on the underlying pathogenesis of bladder overactivity from childhood to adulthood. Our findings could lead to the development of new strategies for the treatment and prevention of adult urinary symptoms arising from childhood urinary tract dysfunction.

Deletion or pharmacological blockade of TLR4 confers protection against cyclophosphamide-induced mouse cystitis

Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS) is a chronic inflammatory disease without consistently effective treatment. We investigate the role of toll-like receptor 4 (TLR4) on voiding dysfunction and inflammation in the cyclophosphamide (CYP)-induced mouse cystitis. Male C57BL/6 [wild-type, (WT)] and/or TLR4 knockout (TLR4^-/-) mice were treated with an injection of CYP (300 mg/kg, 24 h) or saline (10 ml/kg). The pharmacological blockade of the TLR4 by resatorvid (10 mg/kg) was also performed 1 h prior CYP-injection in WT mice. Urodynamic profiles were assessed by voiding stain on filter paper and filling cystometry. Contractile responses to carbachol were measured in isolated bladders. In CYP-exposed WT mice, mRNA for TLR4, myeloid differentiation primary response 88, and TIR-domain-containing adapter-inducing interferon-β increased by 45%, 72%, and 38%, respectively ( P < 0.05). In free-moving mice, CYP-exposed mice exhibited a higher number of urinary spots and smaller urinary volumes. Increases of micturition frequency and nonvoiding contractions, concomitant with decreases of intercontraction intervals and capacity, were observed in the filling cystometry of WT mice ( P < 0.05). Carbachol-induced bladder contractions were significantly reduced in the CYP group, which was paralleled by reduced mRNA for M2 and M3 muscarinic receptors. These functional and molecular alterations induced by CYP were prevented in TLR4^-/- and resatorvid-treated mice. Additionally, the increased levels of inflammatory markers induced by CYP exposure, myeloperoxidase activity, interleukin-6, and tumor necrosis factor-alpha were significantly reduced by resatorvid treatment. Our findings reveal a central role for the TLR4 signaling pathway in initiating CYP-induced bladder dysfunction and inflammation and thus emphasize that TLR4 receptor blockade may have clinical value for IC/BPS treatment.

Benefits of Preventive Administration of Chlorella sp. on Visceral Pain and Cystitis Induced by a Single Administration of Cyclophosphamide in Female Wistar Rat

Chlorella sp. is a green microalgae containing nutrients, vitamins, minerals, and chlorophyll. In some communities, Chlorella sp. is a traditional medicinal plant used for the management of inflammation-related diseases. In a rat model, ROQUETTE Chlorella sp. (RCs) benefits were investigated on visceral pain and associated inflammatory parameters related to cystitis both induced by cyclophosphamide (CYP). RCs was orally administered every day from day 1-16 (250 and 500 mg/kg body weight). Six hours after an intraperitoneal injection of 200 mg/kg body weight of CYP, body temperature, general behavior, food intake, and body weight were recorded. Twenty-four hours after CYP injection, rats were tested in two behavioral tests, an open field and the aversive light stimulus avoidance conditioning test, to evaluate the influence of pain on general activity and learning ability of rats. After euthanasia, bladders were weighed, their thickness was scored, and the urinary hemoglobin was measured. RCs orally administered at the two dosages significantly reduced visceral pain and associated inflammatory parameters related to cystitis both induced by CYP injection, and improved rat behavior. To conclude, RCs demonstrated beneficial effects against visceral pain and cystitis.

A rat long-lasting cystitis model induced by intravesical injection of hydrogen peroxide

Novel longer lasting inflammatory bladder animal models are needed to better understand the pathophysiology of chronic cystitis. We previously developed a relatively long‐lasting mouse cystitis model by intravesical injection of hydrogen peroxide (H₂O₂). To further evaluate its pathophysiology, in this study, we established and analyzed a rat cystitis model. Under anesthesia, 1.5% H₂O₂ solution was introduced transurethrally into the bladder of female rats, and kept for 30 min. The H₂O₂ injection significantly increased the number of micturition events up to day 14 and decreased urine volume per micturition, with the smallest volumes on day 3, compared with the vehicle‐treated group. Cystometric analysis on day 7 revealed that intercontraction intervals were significantly shortened without affecting the baseline, threshold, or maximum pressures. Intravesical resiniferatoxin‐evoked nociceptive behaviors, such as freezing, were significantly enhanced on days 7 and 14. Furthermore, histopathology revealed hemorrhage, edema, infiltration of neutrophils into the lamina propria, and urothelial denudation in the early phase (day 1). These damages were gradually repaired, while hyperplasia of the urothelium, vascularization, increases in fibroblast counts, and infiltration of mast cells and eosinophils were observed through the later phase (days 7 and 14). These results suggest that intravesical H₂O₂ injection induces relatively long‐lasting cystitis with enhanced bladder activity and pain sensation in rats. This approach thus provides a novel rat long‐lasting cystitis model that allows us to analyze detailed symptoms and pathophysiology of H₂O₂‐induced cystitis model than the mouse model and may be used to investigate the pathophysiology and treatment of chronic bladder hypersensitive disorders, such as bladder pain syndrome/interstitial cystitis.

Medicinal Chemistry, Pharmacology, and Clinical Implications of TRPV1 Receptor Antagonists

Transient receptor potential vanilloid 1 (TRPV1) is an ion channel expressed on sensory neurons triggering an influx of cations. TRPV1 receptors function as homotetramers responsive to heat, proinflammatory substances, lipoxygenase products, resiniferatoxin, endocannabinoids, protons, and peptide toxins. Its phosphorylation increases sensitivity to both chemical and thermal stimuli, while desensitization involves a calcium-dependent mechanism resulting in receptor dephosphorylation. TRPV1 functions as a sensor of noxious stimuli and may represent a target to avoid pain and injury. TRPV1 activation has been associated to chronic inflammatory pain and peripheral neuropathy. Its expression is also detected in nonneuronal areas such as bladder, lungs, and cochlea where TRPV1 activation is responsible for pathology development of cystitis, asthma, and hearing loss. This review offers a comprehensive overview about TRPV1 receptor in the pathophysiology of chronic pain, epilepsy, cough, bladder disorders, diabetes, obesity, and hearing loss, highlighting how drug development targeting this channel could have a clinical therapeutic potential. Furthermore, it summarizes the advances of medicinal chemistry research leading to the identification of highly selective TRPV1 antagonists and their analysis of structure-activity relationships (SARs) focusing on new strategies to target this channel.

Urothelial ATP signaling: what is its role in bladder sensation?

AIM

Bladder functional disorders are common health problems; however, their pathologies are poorly understood. Adenosine triphosphate (ATP) released from the urothelium has been suggested to have an essential role in the micturition reflex, and its involvement in bladder functional disorders has been intensively investigated. Here, we review the latest advances in research on urothelial ATP signaling.

METHODS

We reviewed research articles on the role of the urothelium and urothelial ATP release in bladder function.

RESULTS

Mice lacking purinergic receptors have been reported to exhibit marked bladder hyporeflexia. Based on this observation, it was commonly believed, according to the widely held ATP urothelial signaling theory, that stretch-induced urothelial ATP release mediates the sensation of bladder filling via purinergic receptors. However, recent studies employing novel experimental methods and approaches have demonstrated that there are no significant differences in bladder function between wild-type and purinergic receptor knockout mice under physiological conditions. Nonetheless, under pathological conditions, inhibition of purinergic receptors has been shown to improve bladder hyperactivity. Moreover, enhanced urothelial ATP release has been reported in patients with bladder functional disorders.

CONCLUSIONS

Recently, conflicting evidence has led us to question the role of urothelial ATP signaling in normal micturition reflex. In contrast, under pathological conditions, it seems likely that enhanced urothelial ATP signaling mediates bladder hyperactivity. These recent findings suggest that the urothelial ATP signaling pathway is a potential therapeutic target for bladder functional disorders.

Cyclophosphamide-induced Down-Regulation of Uroplakin II in the Mouse Urinary Bladder Epithelium is Prevented by S-Allyl Cysteine

The alkylating anticancer drug, cyclophosphamide (CP), induces a number of toxic effects including haemorrhagic cystitis (HC) in the urinary bladder. Uroplakins are unique urinary transmembrane proteins of urothelium, which may become potential targets of CP metabolites and reactive free radicals. Natural compounds, especially those rich in thiols, have shown protective effects against CP-induced HC. In this study, we studied the modulatory effect of the thiol-rich compound S-allyl cysteine (SAC) on the mRNA level of uroplakin II by real-time polymerase chain reaction and expression of uroplakin II protein by immunoblotting. SAC (150 mg/kg) showed significant (p < 0.001) protective effects against CP (200 mg/kg)-induced alteration in mRNA level and protein expression of uroplakin II. SAC also protected animals from CP-induced HC as assessed by gross morphological examination of urinary bladder. When compared with mercaptoethane sulphonic acid (mesna) (40 mg/kg), a known thiol-rich drug used in clinical application, SAC was found to be more efficacious in affording protection in urinary bladder tissues. Role of uroplakins in CP-induced urinary bladder toxicity has not been well investigated. This study demonstrated that uroplakins may be the potential target of toxic metabolites of CP and natural compounds such as SAC have the capacity to modulate their expression leading to reduced toxicity burden on the urinary bladder epithelium.

Multi-Functional Diarylurea Small Molecule Inhibitors of TRPV1 with Therapeutic Potential for Neuroinflammation

Transient receptor potential vanilloid type 1 (TRPV1), a heat-sensitive calcium channel protein, contributes to inflammation as well as to acute and persistent pain. Since TRPV1 occupies a central position in pathways of neuronal inflammatory signaling, it represents a highly attractive potential therapeutic target for neuroinflammation. In the present work, we have in silico identified a series of diarylurea analogues for hTRPV1, of which 11 compounds showed activity in the nanomolar to micromolar range as validated by in vitro biological assays. Then, we utilized molecular docking to explore the detailed interactions between TRPV1 and the compounds to understand the contributions of the different substituent groups. Tyr511, Leu518, Leu547, Thr550, Asn551, Arg557, and Leu670 were important for the recognition of the small molecules by TRPV1. A hydrophobic group in R2 or a polar/hydrophilic group in R1 contributed significantly to the activities of the antagonists at TRPV1. In addition, the subtle different binding pose of meta-chloro in place of para-fluoro in the R2 group converted antagonism into partial agonism, as was predicted by our short-term molecular dynamics (MD) simulation and validated by bioassay. Importantly, compound 15, one of our best TRPV1 inhibitors, also showed potential binding affinity (1.39 μM) at cannabinoid receptor 2 (CB2), which is another attractive target for immuno-inflammation diseases. Furthermore, compound 1 and its diarylurea analogues were predicted to target the C-X-C chemokine receptor 2 (CXCR2), although bioassay validation of CXCR2 with these compounds still needs to be performed. This prediction from the modeling is of interest, since CXCR2 is also a potential therapeutic target for chronic inflammatory diseases. Our findings provide novel strategies to develop a small molecule inhibitor to simultaneously target two or more inflammation-related proteins for the treatment of a wide range of inflammatory disorders including neuroinflammation and neurodegenerative diseases with potential synergistic effect.

F16357, a novel protease-activated receptor 1 antagonist, improves urodynamic parameters in a rat model of interstitial cystitis

Background and Purpose

The aims of the present study were to characterize the role of PAR1 in rat bladder under inflammatory conditions and determine whether a selective PAR1 antagonist, F16357, can prevent the pathophysiological symptoms of cyclophosphamide‐induced interstitial cystitis (IC).

Experimental Approach

Immunohistochemistry, contractile activity in isolated bladder and urodynamics were determined before and after cyclophosphamide treatment. F16357 was administered intravesically during the acute phase of inflammation, and effects on PAR1 and PAR1‐related bladder contraction evaluated 24 h after cyclophosphamide injection. Urodynamics and associated voided volumes were recorded 7 and 24 h after cyclophosphamide.

Key Results

In control conditions, PAR1 was present only in some umbrella cells. Cyclophosphamide disrupted the urothelium and expression of PAR1 by all remaining urothelial cells. After F16357 treatment, urothelial damage was absent and PAR1 immunoreactivity similar to control tissues. Thrombin and TFLLR‐NH₂ induced bladder contractions. These were increased in inflammatory conditions and antagonized by F16357 in a concentration‐dependent manner. In telemetric experiments, furosemide increased urine production and voiding frequency for 60 min, 7 h after cyclophosphamide injection. Intravesical administration of F16357 blocked these changes with a return to a physiological profile; 24 h after cyclophosphamide, the volume of micturition was still lower with no increase in number of micturitions. F16357 30 μM reduced the number of micturitions and improved bladder capacity, but did not affect diuresis. Under similar experimental conditions, lidocaine 2% induced comparable effects.

Conclusions and Implications

PAR1 is expressed in rat bladder, overactivated in inflammatory conditions and involved in bladder function and sensation. F16357 could represent an interesting candidate for IC treatment.

Bladder telemetry: A new approach to evaluate micturition behavior under physiological and inflammatory conditions

AIMS

To establish a new approach to cystometry using telemetry in conscious rats and to use this technique to determine the role of conscious decision making processes with respect to the initiation of voiding in physiological, inflammatory, and painful conditions.

METHODS

The pressure transducer of a telemetric transmitter was implanted in the dome of the urinary bladder. After a recovery period of at least 1 month, several investigations of urodynamic parameters were performed after diuresis activation by a pulse of furosemide. The model was characterized by tolterodine and mirabegron under physiological conditions and same animals were reused to evaluate the modification of the voiding pattern under bladder inflammation induced by cyclophosphamide.

RESULTS

The quality of traces and measurement of parameters recorded telemetrically were comparable to those with conventional cystometry. Furosemide induced a reproducible transient increase of urine production and a series of voids that persisted for 60 min. Tolterodine reduced the amplitude of micturition contractions although mirabegron was devoid of any effect. Seven hours after injection of CYP, voiding frequency increased significantly and the micturition amplitude contraction was not altered. However, the mean volume voided during individual micturitions and the total voided volume decreased. During a second exposure to furosemide 24H after CYP injection, the micturition pattern returned to control, however, the micturition volume was still lower than in control.

CONCLUSION

This telemetric model appears to be as accurate as previously described in conscious conventional cystometry, and allows the repeated evaluation of compounds which may modulate the voiding patterns. Neurourol. Urodynam. 36:308-315, 2017. © 2016 The Authors. Neurourology and Urodynamics published by Wiley Periodicals, Inc.

Macrophage migration inhibitory factor modulates formalin induced behaviors in rats

Cytokine proteins are involved in different signaling pathways throughout the central nervous system. To study the efficacy of an inflammatory cytokine, the macrophage migration inhibitory factor (MIF), which acts via several receptor molecules including the receptor CXCR2, male rats’ behaviors were determined after intracerebroventricular (ICV) administration of MIF. There were three treatments: One group received only the cytokine, a second group received MIF and an CXCR2 antagonist (SB265610), and a third, control group received only the carrier medium saline. All rats were subjected to a subcutaneous injection of formalin in the hind paw after the ICV administration. Pain behaviors induced after formalin injection showed increased values in the MIF group of licking in the first phase and increased values of flexing, licking and paw-jerk in the second phase. On the contrary, spontaneous behaviors induced by formalin injection changed alternatively between the two groups compared with saline. These results suggest a possible effect of cytokine MIF on central nervous processes implicated in pain modulation mediated by the receptor CXCR2.

Urinary uroplakin expression in cyclophosphamide-induced rat cystitis model

Cyclophosphamide (CYP) induces urothelial injury and causes excretion of cellular exudates at 24 h, followed by rapid restoration at 72 h. We investigated the role of urinary uroplakin II (UPII) levels in a CYP-induced cystitis model. For the purpose of this study, 10 controls and 26 CYP-injected female Sprague Dawley rats were killed at 24 h and 72 h postinjection. The vesical weight, severity of hematuria, and expression of UPII in the urinary bladder and urine were measured. CYP decreased the level of vesical UPII messenger RNA at 24 h, followed by rapid recovery at 72 h. Contrary to the negligible levels of urinary UPII and hematuria in controls, CYP treatment abruptly increased the excretion of urinary UPII at 24 h. The excretion had subsided at 72 h. Similarly, severe hematuria was observed at 24 h, with improvement at 72 h. However, some rats still exhibited hematuria at 72 h. CYP caused increase in vesical weight. The vesical weight at 24 h after CYP injection was negatively correlated with the vesical UPII level. Rats with significant hematuria demonstrated higher urinary UPII levels than those with insignificant hematuria. Vesical UPII could be an important barrier for early CYP-related injury, while the levels of urinary UPII may be associated with the severity of hematuria during dynamic periods in the urothelium.

Urinary bladder inflammation induces changes in urothelial nerve growth factor and TRPV1 channels

BACKGROUND AND PURPOSE

The urinary bladder urothelium expresses various receptors and in response to chemical and mechanical stimuli releases mediators, thereby modulating bladder sensory pathways. Transient receptor potential vanilloid 1 (TRPV1) ion channels and nerve growth factor (NGF) in those cells are implicated in this modulatory effect and play a role in sensitizing pain-related afferent pathways during inflammation. In this study, we investigated the interaction between NGF and TRPV1 channels in urothelial cells.

EXPERIMENTAL APPROACH

Urothelial cells from female Sprague-Dawley rat bladders were cultured to quantify membrane expression of TRPV1 channels and capsaicin-induced ATP release in the presence of NGF alone or with TrKA or PI3K inhibitors. Pain scores from rats with cyclophosphamide (CYP)-induced bladder inflammation were assessed after treatment with a TrkA antagonist. Bladders (from control and CYP rats) were collected and analysed for NGF content and TRPV1 channel expression.

KEY RESULTS

Cultured cells responded to NGF with increased TRPV1 channel expression in the cell membrane and increased release of ATP. Both responses were blocked by either a TrkA antagonist or a PI3K inhibitor. Treatment in vivo with the TrkA antagonist alleviated pain symptoms and reduced CYP-induced NGF overexpression in the mucosa. Furthermore, in urothelial cells from animals with bladder inflammation, expression of TRPV1 channels in the membrane was significantly increased.

CONCLUSIONS AND IMPLICATIONS

During bladder inflammation, increased production of NGF in urothelial cells induced increased expression and activity of TRPV1 channels in the cell membrane. This effect was primarily mediated by the PI3K pathway.

Spinal blockage of P/Q- or N-type voltage-gated calcium channels modulates functional and symptomatic changes related to haemorrhagic cystitis in mice

BACKGROUND AND PURPOSE

Spinal voltage-gated calcium channels (VGCCs) are pivotal regulators of painful and inflammatory alterations, representing attractive therapeutic targets. We examined the effects of epidural administration of the P/Q- and N-type VGCC blockers Tx3-3 and Phα1β, respectively, isolated from the spider Phoneutria nigriventer, on symptomatic, inflammatory and functional changes allied to mouse cyclophosphamide (CPA)-induced haemorrhagic cystitis (HC). The effects of P. nigriventer-derived toxins were compared with those displayed by MVIIC and MVIIA, extracted from the cone snail Conus magus.

EXPERIMENTAL APPROACH

HC was induced by a single i.p. injection of CPA (300 mg·kg(-1) ). Dose- and time-related effects of spinally administered P/Q and N-type VGCC blockers were assessed on nociceptive behaviour and macroscopic inflammation elicited by CPA. The effects of toxins were also evaluated on cell migration, cytokine production, oxidative stress, functional cystometry alterations and TRPV1, TRPA1 and NK1 receptor mRNA expression.

KEY RESULTS

The spinal blockage of P/Q-type VGCC by Tx3-3 and MVIIC or N-type VGCC by Phα1β attenuated nociceptive and inflammatory events associated with HC, including bladder oxidative stress and cytokine production. CPA produced a slight increase in bladder TRPV1 and TRPA1 mRNA expression, which was reversed by all the toxins tested. Noteworthy, Phα1β strongly prevented bladder neutrophil migration, besides HC-related functional alterations, and its effects were potentiated by co-injecting the selective NK1 receptor antagonist CP-96345.

CONCLUSIONS AND IMPLICATIONS

Our results shed new light on the role of spinal P/Q and N-type VGCC in bladder dysfunctions, pointing out Phα1β as a promising alternative for treating complications associated with CPA-induced HC.

The pharmacology of TRP channels

This themed issue of the British Journal of Pharmacology contains review and research articles on recent advances in transient receptor potential (TRP) channel pharmacology. The review articles, written by a panel of distinguished experts, address the rapid progress in TRP channel research in fields as diverse as oncology, urology, dermatology, migraine, inflammation and pain. These reviews are complemented by original research reports focusing, among others, on the emerging roles of TRPV1 in osteoporosis and cystitis and on evodiamine as a lead structure for the development of potent TRPV1 agonists/desensitizers. Other papers highlight the differences in TRPV3 pharmacology between recombinant and native systems, the mechanisms of TRPM3 activation/inhibition and TRPP2 as a target of naringenin, a dietary flavonoid with anticancer actions. New therapeutic opportunities in pain may arise from the strategy to combine TRP channel and cell membrane impermeant sodium channel blockers to inhibit sensory nerve activity.

Pharmacological inhibition of CXCR2 chemokine receptors modulates paraquat-induced intoxication in rats

Paraquat (PQ) is an agrochemical agent commonly used worldwide, which is allied to potential risks of intoxication. This herbicide induces the formation of reactive oxygen species (ROS) that ends up compromising various organs, particularly the lungs and the brain. This study evaluated the deleterious effects of paraquat on the central nervous system (CNS) and peripherally, with special attempts to assess the putative protective effects of the selective CXCR2 receptor antagonist SB225002 on these parameters. PQ-toxicity was induced in male Wistar rats, in a total dose of 50 mg/kg, and control animals received saline solution at the same schedule of administration. Separate groups of animals were treated with the selective CXCR2 antagonist SB225002 (1 or 3 mg/kg), administered 30 min before each paraquat injection. The major changes found in paraquat-treated animals were: decreased body weight and hypothermia, nociception behavior, impairment of locomotor and gait capabilities, enhanced TNF-α and IL-1β expression in the striatum, and cell migration to the lungs and blood. Some of these parameters were reversed when the antagonist SB225002 was administered, including recovery of physiological parameters, decreased nociception, improvement of gait abnormalities, modulation of striatal TNF-α and IL-1β expression, and decrease of neutrophil migration to the lungs and blood. Taken together, our results demonstrate that damage to the central and peripheral systems elicited by paraquat can be prevented by the pharmacological inhibition of CXCR2 chemokine receptors. The experimental evidence presented herein extends the comprehension on the toxicodynamic aspects of paraquat, and opens new avenues to treat intoxication induced by this herbicide.

TRPV1: A Potential Drug Target for Treating Various Diseases

Transient receptor potential vanilloid 1 (TRPV1) is an ion channel present on sensory neurons which is activated by heat, protons, capsaicin and a variety of endogenous lipids termed endovanilloids. As such, TRPV1 serves as a multimodal sensor of noxious stimuli which could trigger counteractive measures to avoid pain and injury. Activation of TRPV1 has been linked to chronic inflammatory pain conditions and peripheral neuropathy, as observed in diabetes. Expression of TRPV1 is also observed in non-neuronal sites such as the epithelium of bladder and lungs and in hair cells of the cochlea. At these sites, activation of TRPV1 has been implicated in the pathophysiology of diseases such as cystitis, asthma and hearing loss. Therefore, drugs which could modulate TRPV1 channel activity could be useful for the treatment of conditions ranging from chronic pain to hearing loss. This review describes the roles of TRPV1 in the normal physiology and pathophysiology of selected organs of the body and highlights how drugs targeting this channel could be important clinically.