Mast cells are important regulator of acupoint sensitization via the secretion of tryptase, 5-hydroxytryptamine, and histamine.

Ning Ding,Zhigang Li,Pingping Qin,Jiatong Hu,Qiaoxia Wang,Jing Jiang,Vincenzo Miragliotta

doi:10.1371/journal.pone.0194022

Abstract

Mast cells (MCs) play a crucial role in mediating the establishment of networks among the circulatory, nervous and immune system at acupoints. However, the changes which occur in MCs during acupoint sensitization, i.e. the dynamic transformation of an acupoint from a "silenced" to an "activated" status, remain uncharacterized. To investigate the morphological and functional changes of MCs as an aid to understanding the cellular mechanism underlying acupoint sensitization, a rat model of knee osteoarthritis (OA) was induced by an injection of mono-iodoacetate (MIA) on day 0. On day 14, toluidine blue and immunofluorescence staining were used to observe the recruitment and degranulation of MCs and the release of mast cell co-expressed mediators: tryptase, 5-hydroxytryptamine (5-HT) and histamine (HA) at the acupoints Yanglingquan (GB34), Heding (EX-LE2) and Weizhong (BL40). Results showed that the number of MCs as well as the percentages of degranulated and extensively degranulated MCs at the acupoints GB34 and EX-LE2 in the light (A), mild (B), heavy (C) osteoarthritis groups were larger than those in the normal control (N) and normal saline (NS) groups (p < 0.01). Comparisons among the A, B and C groups suggested that the number and the degranulation extent of the MCs at the acupoints GB34 and EX-LE2 were positively correlated with the severity of the disease. Some MCs in the A, B and C group showed the release of 5-HT, HA, and tryptase in degranulation at the acupoints GB34 and EX-LE2. Such changes in MCs were not observed at the acupoint BL40. In conclusion, this study confirmed that acupoint sensitization is associated with the increase in recruitment and degranulation levels of MCs on a acupoint-specific and disease severity-dependent manner. The release of tryptase, 5-HT, and HA during MC degranulation is likely to be one of the cellular mechanisms occurring during acupoint sensitization.

Highlights

Mast cells (MCs) are important components of the immune system, widely viewed as potential effector cells in acupuncture
This study strongly suggests that early diagnosis as well as disease progression monitoring can be achieved through the observation of the dynamical changes occurring during acupoint sensitization at particular acupoints since the degrees of acupoint sensitization and disease severity were closely correlated
In view of the previous findings and the current results, we propose that the increase in recruitment and degranulation levels of MCs during acupoint sensitization may be the result of complex interactions between the circulatory, nervous and immune systems, which are location, and disease severity-dependent

Summary

Introduction

Mast cells (MCs) are important components of the immune system, widely viewed as potential effector cells in acupuncture. The effects of mast cells on acupoint sensitization function of MCs in the colon mediate the effects accomplished by acupuncture on the improvement of the irritable bowel syndrome [1,2]. The functional and morphological changes of MCs during the acupoint sensitization upon different diseases and levels of disease severity have been neglected to a certain extent and remain largely elusive. The dynamics of the acupoint response to disease are confined to the term “acupoint sensitization”. It refers to the dynamic transformation of an acupoint from a "silenced status" (as induced by healthy conditions) to an "activated status” (as induced by disease) [7,10]. As disease indicators located on the body surface, sensitized acupoints can be used in clinical prognosis and disease monitoring practices [13,14]

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