An involvement of neurokinin-1 receptor in FcεRΙ-mediated RBL-2H3 mast cell activation

Aprepitant Inhibits JNK and p38/MAPK to Attenuate Inflammation and Suppresses Inflammatory Pain

Substance P contributes to the pathogenesis of pain by acting on NK-1R, specialized sensory neurons that detect noxious stimuli. Aprepitant, an antagonist of NK-1R, is widely used to treat chemotherapy-induced nausea and vomiting. In this study, we used LPS-stimulated BV-2 microglia cell line and animal models of inflammatory pain to explore the analgesic effect of aprepitant on inflammatory pain and its underlying mechanism. The excitability of DRG neurons were measured using whole-cell patch-clamp recordings. The behavioral tests were measured and the morphological changes on inflamed paw sections were determined by HE staining. Changes in the expressions of cytokine were measured by using real-time quantitative PCR analysis and ELISA method. Immunofluorescence and western blotting were used to detect the microglia activation and MAPK. Aprepitant treatment significantly inhibited the excitability of DRG neurons. The pain behavior and the paw tissues inflammatory damage were significantly relived after the administration of aprepitant compared to formalin group. Aprepitant significantly suppressed the activation of microglia, phosphorylation of JNK and p38 MAPK, as well as the mRNA and protein expressions of MCP-1, TNF-α, IL-6, and IL-1β, in vivo and in vitro. The LPS-induced over-translocation into nucleus of NF-κBp65 was down-regulated following aprepitant treatment in BV-2 cells. The present study suggests that aprepitant attenuates inflammatory pain in mice via suppressing the phosphorylation of JNK and p38, and inhibiting the NF-κB signaling pathway.

Current views on neuropeptides in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease involving skin barrier dysfunction and immune imbalance. However, the mechanism of AD is not clear completely and may be related to heredity and environment. Neuropeptides are a class of peptides secreted by nerve endings, they may play roles in promoting vasodilation, plasma extravasation, chemotaxis of inflammatory cells and mediating pruritus. Since itching and immune cell infiltration are the main manifestations of atopic dermatitis, to further investigate the impact of neuropeptides on AD, our review summarized the mechanisms of several common neuropeptides in AD and hypothesized that neuropeptides may be the novel potential targets in AD treatment.

Glucocorticoid treatment inhibits intracerebral hemorrhage‑induced inflammation by targeting the microRNA‑155/SOCS‑1 signaling pathway

Intracerebral hemorrhage (ICH) results in inflammation, and glucocorticoids have been proven to be effective inhibitors of ICH‑induced inflammation. However, the precise underlying mechanisms of ICH‑induced inflammation and glucocorticoid function remain largely undefined. Using a mouse ICH model, the present study demonstrated that the short non‑coding RNA molecule microRNA‑155 (miR‑155) is involved in the inflammatory process initiated by ICH in mice. Increased mRNA expression levels of miR‑155, as well as the pro‑inflammatory cytokines interferon‑β (IFN‑β), tumor necrosis factor‑α (TNF‑α) and interleukin‑6 (IL‑6), were observed in vivo following ICH. By contrast, the expression level of suppressor of cytokine signaling 1 (SOCS‑1) protein was reduced in the ICH group compared with control mice. Similar results were observed in vitro using astrocytes, the primary effector cells in ICH. Compared with wild type astrocytes, astrocytes overexpressing miR‑155 exhibited significant inhibition of SOCS‑1 protein expression levels. These results suggest that miR‑155 contributes to the development of ICH‑induced inflammation in mice by downregulating SOCS‑1 protein expression levels and promoting pro‑inflammatory cytokine (IFN‑β, TNF‑α and IL‑6) production. Expression levels of miR‑155 and pro‑inflammatory cytokines in the ICH group were significantly decreased following dexamethasone administration. This suggests that glucocorticoids attenuate ICH‑induced inflammation by targeting the miR‑155/SOCS‑1 signaling pathway in mice. In conclusion, the results of the present study demonstrated that the miR‑155/SOCS‑1 signaling pathway is required for ICH‑induced inflammation, and glucocorticoids inhibit this process by targeting the miR‑155/SOCS‑1 signaling pathway.

Knockdown of neurokinin-1 receptor expression by small interfering RNA prevents the development of allergic rhinitis in rats

Objective and design

This study is aimed at exploring the role of neurokinin-1 receptor (NK-1R) in the development of allergic rhinitis (AR) in rats.

Methods

Sprague–Dawley rats were sensitized and challenged with ovalbumin to induce AR. The rats were treated intranasally with saline, control, or NK-1R-specific small interfering RNA (siRNA) before and during the challenge period. The numbers of sneezes and nose rubs and amount of nasal secretion in individual rats were measured. The levels of NK-1R expression in the nasal mucosal tissues after the last challenge were determined. The numbers of eosinophils in the collected nasal lavage fluid and the levels of serum interleukin (IL)-5 in individual rats were determined.

Results

The levels of NK-1R expression in the nasal mucosal tissues of the AR rats that had been treated with saline or control siRNA were significantly higher than those in the healthy controls and the rats treated with NK-1R-specific siRNA, demonstrating NK-1R silencing. Furthermore, knockdown of NK-1R expression significantly reduced the amounts of sneezing, nose rubbing, and nasal secretions in AR rats. Knockdown of NK-1R expression also significantly eliminated eosinophil infiltration in the nasal tissues and reduced the levels of serum IL-5 in rats.

Conclusions

Knockdown of NK-1R expression decreased allergic inflammation in nasal mucosal tissues and alleviated the allergic rhinitis symptoms, suggesting that NK-1R may be a critical mediator of the development of AR.