| ?Objective?Pruritus can be a seriously debilitating symptom, representing one of the most prominent clinical features in numerous liver disorder, such as primary biliary cirrhosis(PBC), primary sclerosing cholangitis(PSC), cholangiocarcinoma(CCC) and intrahepatic cholestasis of pregnancy. This form of itching is designated cholestatic pruritus. The molecular mechanisms involved in the pathogenesis of cholestatic pruritus remain enigmatic, and treatment of these patients often represents a clinical challenge because of limited therapeutic options. In this study we highlight the potential role of lysophosphatidic acid(LPA) in pruritus of cholestasis by clinical trials and animal experiments.?Methods?1?Inpatients diagnosed as jaundice were recruited in this study, in the Eastern Hepatobiliary Surgery Hospital. Follow-up and summarize the clinical characteristics of cholestasis pruritus. Patients were asked to rate their experience of pruritus using a visual analogue scale(VAS)2?LPA in plasma obtained from healthy donors and patients with or without cholestatic pruritus was analyzed by high-performance liquid chromatography/mass spectroscopy(LC-MS/MS).3?C57BL/6 mice were intradermally injected with LPA, as well as the same treatment in patients with or without cholestasis pruritus, evaluating whether LPA could act as a pruritogen directly.4?Three kinds of behavior experiments including intradermally injection mixed with LPA?LPA pretreatment via tail vein as well as DRG, were applied in mice to prove that whether LPA could facilitate pruritus.?Results?1?Evaluation of clinical characteristics in cholestasis pruritus and detection of LPA in plasma as well as correlational analyses between LPA leval and itch intensity.1.1?68.0%(104/153)patients in cholestatic disorders were suffered from pruritus. 84.9%(62/73)cholestasis pruritus develop in the early stage of jaundice or even earlier than the appearance of jaundice. The worsening of pruritus in night was found in 84.9(62/73)cholestasis pruritus, and it would affect sleep in severe cases. The symptom could occurr in the palm, trunk or lower limb, even systemically. No significant difference was found in the sex between the two groups.1.2?The diurnal pruritus severity was recorded on a visual analogue scale(VAS). Itch intensity was improved in three groups on the first day undergoing ERCP. The patients with mild pruritus had no sensible pruritus on third day after ERCP. The patients with moderate and severe pruritus perceived weakly five days after received ERCP, and barely detectable on the seventh and tenth day respectively.1.3?Analyzed by high-performance liquid chromatography/mass spectroscopy(LC-MS/MS), we observed higher LPA activity in plasma from patients with pruritus due to cholestasis as compared with patients without pruritus and non-cholestasis controls. LPA decreased significantly on the second and fifth day respectively after ERCP when compared with pre-ERCP.1.4?We found a highly significant correlation between LPA and intensity of itch perception by spearman rank correlation analysis, which suggested that LPA act importantly in the development of cholestasis pruritus. Even though there exist just low correlation between TBA and itch intensity, cholestatic patients with pruritus showed higher serum TBA concentration, so the possibility of TBA cannot be ruled out. In contrast, TBIL did not show any correlation with itch intensity in our patient cohort.2?Intradermal injections of LPA could not induce scratching behavior shown as number of scratching bouts, but just pain behavior shown as numbers of wipes, no matter in BDL mice, cholestatic patients or volunteers.2.1?Exploration on the mice model of choletstasis pruritus. It is successful for BDL mice model to simulate cholestatic state in patients, but there was no enhanced scratching behavior in BDL mice. Besides, LPA content in mice plasma did not show any difference from the sham group. These results remind us that the development of cholestasis pruritus is indeed inseparable from the increased LPA in plasma.2.2?Intradermal LPA injections(1nmol?55nmol 3 to 100nmol/site) induced dose-dependent bouts of and wipes within a short time, but not scratching, both in BDL and sham mice. BDL mice exhibited attenuated pain behavior compared with sham mice, possibly because of the hyperalgesia in BDL mice.2.3?Intradermal different concentrations of LPA in volunteers just evoked dose-depedent pain sensation as well as in cholestasis pruritus patients and cholestasis without pruritus, but failed to evoke any itch sensations. Besides, cholestasis subjects exhibited attenuated pain response compared with volunteers, possibly because of the hyperalgesia in cholestasis.3?LPA acts as a modulator to facilitate cholestasis pruritus3.1?Intradermal injections of CQ mixed with LPA in C57BL/6 mice,cheek induced significant potentiated scratching behavior, with no effect on Histamine. The function of facilitation was mainly embodied in potentiating the pruritic effect of CQ in every period of time.3.2?In C57BL/6 mice, pretreatment with LPA for 15 mins via tail vein significantly potentiated scratching behavior to above two times evoked by intradermal injections of CQ rather than histamine. Besides, the main function of the facilitation included potentiating the pruritic effect of CQ effectively in every period of time and prolong action time of CQ.3.3?LPA pre-incubation in C57BL/6 mice,DRG could facilitate the scratching behavior evoked by CQ not histamine. The facilitation of CQ was mainly embodied in potentiating the pruritic effect in every period of time.At the end of this part it comes to the conclusion that, LPA could significantly potentiate the effect of CQ other than histamine via enhancing the pruritus in every period of time as well as prolong the action time of CQ. Therefore, we hypothesized that non-histaminergic pathways was involved in the facilitation effect of LPA.In conclusion, plasma LPA activity is specifically increased in patients with cholestasis, but not controls, and plasma LPA is highly correlated itch intensity, which was not involved in BDL mice whose spontaneous itch behavior was not enhanced. These results indicated that LPA acts importantly in the development of cholestasis pruritus. Furthermore, LPA acts as a modulator to facilitate the pruritic effects of other non-histaminergic pruritogens, such as CQ, but not acts directly as a pruritic agent. Thus, we suggest that cholestasis pruritus may be an integrated result of direct pruritic effect of some pruritogens, possibly serum TBA, and the facilitation of LPA in plasma. |
PDF Full Text Request