Notch1 Signaling Contributes to Mechanical Allodynia Associated with Cyclophosphamide-Induced Cystitis by Promoting Microglia Activation and Neuroinflammation

Involvement of NOTCH1-mediated Microglia Activation in Neuromodulation of Chronic Prostatitis-related Pain

BACKGROUND/AIM

This study aimed to investigate the role of NOTCH receptor 1 (NOTCH1)-mediated activation of microglia in the L5-S2 spinal dorsal horn in chronic prostatitis pain.

MATERIALS AND METHODS

Rats were divided into chronic prostatitis (CP) group and control group. Complete Freund's adjuvant was injected into the prostate, and prostate pathology and pain-related behavior were monitored to assess the successful establishment of the CP-related pain model. The dorsal horn of the L5-S2 spinal cord was collected for the detection of ionized calcium-binding adapter molecule 1 (IBA-1) and NOTCH1 expression by quantitative real time polymerase chain reaction and the detection of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) by enzyme-linked immunosorbent assay. Electrical excitability was assessed with whole-cell patch clamp. In addition, NOTCH1 receptor inhibitor or inhibitor of microglial cell activation was injected into the subarachnoid space, and the pro-inflammatory cytokines in the spinal cord were detected.

RESULTS

In the CP group, the expression of NOTCH1, IBA-1, TNF-α and IL-1β began to increase at 4 days, peaked at 12 days, and began to decline at 24 days, and it was significantly higher than in the control group (p<0.01). Inhibition of microglia or NOTCH1 receptor markedly reduced the content of TNF-α and IL-1β in the spinal cord (p<0.05). At 4, 12 and 24 days, the amplitude and frequency of neuronal action potential increased and the threshold decreased markedly as compared to the control group (p<0.05), and spontaneous action potential was noted.

CONCLUSION

NOTCH1 mediates the activation of microglia in the L5-S2 spinal cord, leading to the secretion of inflammatory factors and enhanced electrical excitability of neurons, which is related to persistent and refractory chronic prostatitis-related pain.

Uroprotective and pain-relieving effect of dietary supplementation with micronized palmitoyl-glucosamine and hesperidin in a chronic model of cyclophosphamide-induced cystitis

Introduction

Feline idiopathic cystitis is a common, chronic-relapsing disorder of the lower urinary tract. In addition to environmental modification/enrichment, long-term and safe treatment targeting specific pathophysiological changes may be of help. In this context, effective dietary interventions hold clinical promise. Palmitoyl-glucosamine (PGA) and hesperidin (HSP) are safe and authorized feed ingredients for animal nutrition under European regulations.

Methods

The current study aimed to investigate whether a 3:1 mixture of micronized PGA and HSP could represent a novel mechanism-oriented approach to chronic cystitis management. A newly validated rat model of cyclophosphamide (CYP)-induced chronic cystitis was used (40 mg/kg, three intraperitoneal injections every 3rd day). Animals were randomized to orally receive either vehicle or PGA-HSP at a low (72 + 24 mg/kg) or high (doubled) dose for 13 days, starting 3 days before the chronic CYP protocol, with mesna (2-mercaptoethane-sulfonate) being used as a reference drug.

Results

Higher PGA-HSP dose was effective at relieving chronic visceral pain, as measured by mechanical allodynia test (von Frey test). The severity of cystitis was also significantly improved, as shown by the reduced sonographic thickening of the bladder wall, as well as the decrease in edema, bleeding and bladder to body weight ratio compared to the vehicle treated group. A significant decrease of MPO activity, MDA level and fibrosis at Masson's trichrome staining was also observed in animals administered PGA-HSP in comparison to vehicle treated ones. The CYP-induced increase in bladder mRNA expression of pro-inflammatory cytokines was also significantly counteracted by the study mixture. Moreover, CYP-induced bladder mast cell accumulation and releasability were significantly decreased by PGA-HSP (even at the low dose), as determined by metachromatic staining, chymase and tryptase immunostaining as well as enzyme-linked immunosorbent assay for histamine and 5-hydoxytriptamine.

Discussion

PGA-HSP is able to block CYP-induced decrease of tight junction proteins, claudin-1 and occludin, thus preserving the urothelial bladder function. Finally, neuroinflammatory changes were investigated, showing that dietary supplementation with PGA-HSP prevented the activation of neurons and non-neuronal cells (i.e., microglia, astrocytes and mast cells) at the spinal level, and counteracted CYP-induced increase of spinal mRNA encoding for pro-inflammatory cytokines. Altogether, the present findings confirm the uroprotective and pain-relieving effect of PGA-HSP and pave the way to potential and relevant clinical applications of the study supplement in feline idiopathic cystitis.

Bone marrow mesenchymal stem cell-derived exosomes shuttling miR-150-5p alleviates mechanical allodynia in rats by targeting NOTCH2 in microglia

Background

This study probes into the function and mechanism of bone marrow mesenchymal stem cell (BMSC)-derived exosomes loaded with miR-150-5p in mechanical allodynia.

Methods

BMSCs were infected with miR-150-5p inhibition lentiviruses to obtain exosomes with low miR-150-5p expression. A L5 spinal nerve ligation (SNL) model was established in rats where exosomes, NOTCH2 overexpression/inhibition plasmids, or microglial cells were intrathecally administered. Hind paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) of rats were measured. TUNEL staining was used to measure the apoptotic rate in rat spinal dorsal horn (SDH), ELISA to evaluate pro-inflammatory factor levels, and RT-qPCR, western blotting, and immunohistochemistry to detect miR-150-5p and NOTCH2 expression. Immunofluorescence was used for localizing exosomes and NOTCH2 and detecting the expression of OX42, a maker for microglia. Dual luciferase reporter and RNA pull down assays were performed to validate the putative binding between miR-150-5p and NOTCH2.

Results

NOTCH2 expressed at a high level and miR-150-5p was downregulated in SDH of SNL rats. Exosomes injected were localized in rat SDH. BMSC-exosomes or NOTCH2 downregulation increased PWT and PWL of SNL rats and reduced apoptosis and inflammation in SDH. In contrast, NOTCH2 overexpression aggravated mechanical allodynia and SDH injury. Moreover, inhibiting miR-150-5p in BMSC-exosomes offset the therapeutic effects of BMSC-exosomes. Microglia activation induced mechanical allodynia in wild rats, while intrathecal injection of microglial cells incubated with BMSC-exosomes showed alleviated mechanical allodynia in SNL rats. NOTCH2 was targeted by miR-150-5p.

Conclusion

BMSC-derived exosomal miR-150-5p alleviates mechanical allodynia by targeting NOTCH2 in microglial cells.

Broaden Horizons: The Advancement of Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating disease that induces mental stress, lower urinary symptoms, and pelvic pain, therefore resulting in a decline in quality of life. The present diagnoses and treatments still lead to unsatisfactory outcomes, and novel diagnostic and therapeutic modalities are needed. Although our understanding of the etiology and pathophysiology of IC/BPS is growing, the altered permeability of the impaired urothelium, the sensitized nerves on the bladder wall, and the chronic or intermittent sensory pain with inaccurate location, as well as pathologic angiogenesis, fibrosis, and Hunner lesions, all act as barriers to better diagnoses and treatments. This study aimed to summarize the comprehensive information on IC/BPS research, thereby promoting the progress of IC/BPS in the aspects of diagnosis, treatment, and prognosis. According to diverse international guidelines, the etiology of IC/BPS is associated with multiple factors, while the presence of Hunner lesions could largely distinguish the pathology, diagnosis, and treatment of non-Hunner lesions in IC/BPS patients. On the basis of the diagnosis of exclusion, the diverse present diagnostic and therapeutic procedures are undergoing a transition from a single approach to multimodal strategies targeting different potential phenotypes recommended by different guidelines. Investigations into the mechanisms involved in urinary symptoms, pain sensation, and bladder fibrosis indicate the pathophysiology of IC/BPS for further potential strategies, both in diagnosis and treatment. An overview of IC/BPS in terms of epidemiology, etiology, pathology, diagnosis, treatment, and fundamental research is provided with the latest evidence. On the basis of shared decision-making, a multimodal strategy of diagnosis and treatment targeting potential phenotypes for individual patients with IC/BPS would be of great benefit for the entire process of management. The complexity and emerging evidence on IC/BPS elicit more relevant studies and research and could optimize the management of IC/BPS patients.