Conditioning pain stimulation does not affect itch induced by intra-epidermal histamine pricks but aggravates neurogenic inflammation in healthy volunteers

This study investigated whether itch induced by intra-epidermal histamine is subjected to modulation by a standardized conditioned pain modulation (CPM) paradigm in 24 healthy volunteers. CPM was induced by computer-controlled cuff pressure algometry and histamine was introduced to the volar forearm by skin prick test punctures. Moreover, neurogenic inflammation and wheal reactions induced by histamine and autonomic nervous system responses (heart rate variability and skin conductance) were monitored. CPM did not modulate the intensity of histamine-induced itch suggesting that pruriceptive signaling is not inhibited by pain-recruited endogenous modulation, however, CPM was found to aggravate histamine-induced neurogenic inflammation, likely facilitated by efferent sympathetic fibers.     

H3受体在5-羟色胺诱导大鼠瘙痒初级传入通路中作用

目的观察H3受体激动剂（R-α-甲基组胺）和拮抗剂（噻普酰胺）对5-羟色胺（5-HT）诱导大鼠搔抓行为的影响,并探讨H3受体在大鼠瘙痒初级传入通路中的作用。方法29只SD大鼠随机分为4组,分别在颈背部皮内注射生理盐水（生理盐水组）、2%5-HT（5-HT组）、R-α-甲基组胺＋5-HT（甲基组胺组）、噻普酰胺＋5-HT（噻普酰胺组）,摄像并计数注射后1 h内搔抓次数。取大鼠C3-C5及其相应节段的背根神经节（DRG）作H3R免疫组化染色。结果5-HT组大鼠的搔抓次数明显多于生理盐水组（P〈0.01）,而R-α-甲基组胺或噻普酰胺预处理可分别减少或增加大鼠搔抓次数（P〈0.01）。5-HT组大鼠脊髓后角浅层中H3受体表达与生理盐水组相比差异无显著性（P〉0.05）,而R-α-甲基组胺或噻普酰胺预处理可分别减少或增加H3受体表达（P〈0.01-0.05）。各组动物DRG内,H3受体阳性中、小型神经细胞的比值差异无统计学意义（P〉0.05）。结论在5-HT诱导大鼠急性瘙痒模型中,脊髓背角胶状质区内H3受体激活可减弱瘙痒,但DRG内中、小型神经细胞上H3受体表达可能不参与瘙痒信号的传导。     

Scratching of their skin by NC/Nga mice leads to development of dermatitis

Effects of scratching behavior on dermatitis, transepidermal water loss (TEWL) and serum IgE concentrations were examined in NC/Nga (NC) mice with toenails (WIT) and without toenails (WOT). The first study was a preventive treatment done to cut off hind toenails before dermatitis induction and the second study was a therapeutic treatment by cutting off hind toenails of NC mice with severe dermatitis. In the preventive study, scratching behavior significantly increased in both WIT and WOT after dermatitis induction. Skin severity score, TEWL, number of mast cells and serum IgE concentration statistically increased in WIT but not in WOT after dermatitis induction. Histological changes coincided with the skin severity score in WIT, while no changes were observed in WOT. In the therapeutic study, skin severity score in WOT but not in WIT statistically decreased after cutting off the hind toenails. TEWL and numbers of mast cells in WOT were statistically lower compared with findings in WIT. Thus scratching up the skin with toenails seemed to be the most important factor leading to dermatitis in NC mice.     

The ubiquitin‐editing enzyme A20 requires RNF11 to downregulate NF‐κB signalling

The RING domain protein RNF11 is overexpressed in breast cancers and promotes tumour growth factor‐beta (TGF‐β) signalling. RNF11 has been proposed to regulate TGF‐β signalling by interacting with HECT‐ and SCF‐type E3 ligases; however, the role of RNF11 in other signalling pathways is poorly understood. Here, we demonstrate a novel function of RNF11 as a negative regulator of NF‐κB and jun N‐terminal kinase (JNK) signalling pathways. Knockdown of RNF11 with siRNA resulted in persistent tumour necrosis factor (TNF)‐ and lipopolysaccharide (LPS)‐mediated NF‐κB and JNK signalling. RNF11 interacted with the NF‐κB inhibitor A20 and its regulatory protein TAX1BP1 in a stimulus‐dependent manner. RNF11 negatively regulated RIP1 and TRAF6 ubiquitination upon stimulation with TNF and LPS, respectively. Furthermore, RNF11 was required for A20 to interact with and inactivate RIP1 to inhibit TNF‐mediated NF‐κB activation. Our studies reveal that RNF11, together with TAX1BP1 and Itch, is an essential component of an A20 ubiquitin‐editing protein complex that ensures transient activation of inflammatory signalling pathways.     

Interaction between cFLIPL and Itch,a ubiquitin ligase,is obstructed in Trypanosoma cruzi‐infected human cells

Death receptor‐mediated host cell apoptosis, a defense strategy for elimination by the immune system of parasite‐infected cells, is inhibited by Trypanosoma cruzi, the causative agent of Chagas' disease. It has previously been reported by us that, in infected cells, T. cruzi upregulates and exploits cFLIP_L, a mammalian inhibitor of death receptor signaling. Here it is shown that ubiquitination of cFLIP_L, leading to proteasomal degradation, is inhibited in parasite‐infected cells. The extent of expression of Itch, a protein thought to be an ubiquitin ligase for cFLIP_L, was found to be equivalent in T. cruzi‐infected and in uninfected cells. However, co‐immunoprecipitation analysis showed that the interaction between cFLIP_L and Itch is strongly inhibited in T. cruzi‐infected cells. This unique parasite strategy, which has not been reported in any other pathogen‐infected cells, may allow the host cell to accumulate cFLIP_L, eventually resulting in the inhibition of apoptosis of T. cruzi‐infected cells.     

泛素连接酶对Notch 信号途径的调节作用

Notch信号途径是生物进化过程中高保守的信号通路,对细胞的定向发育及成熟起到决定性的作用。Notch信号途径受到多种分子机制的严格调控。近年来,多项研究均突出了泛素化在调控Notch信号途径活性中的重要性。本文就四种E3泛素连接酶Su(dx)/Itch、Sel-10、LNX以及Neuralized对于调控Notch受体及Notch信号途径配体的研究现况作一综述。     

蚊虫叮咬止痒消炎剂的研制及应用

目的研制蚊虫叮咬止痒消炎剂,观察应用该蚊虫叮咬止痒消炎剂对吉林洮南地区背点伊蚊和刺扰伊蚊叮咬后的治愈效果。方法药品制备采用渗漉法和超声波提取法,质量控制依据中华人民共和国国家标准《一次性使用卫生用品卫生标准》GB 15979-2002,效果观察采用局部外用涂抹法。结果该止痒消炎剂12、24和48 h平均痊愈率分别为24.30%、55.14%和17.76%,总有效率为97.20%。结论该蚊虫叮咬止痒消炎剂符合中华人民共和国国家标准《一次性使用卫生用品卫生标准》GB 15979-2002的规定,对吉林洮南地区优势蚊种叮咬后具有明显的治愈效果,适用于部队野外执行任务携带。