期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2021
卷号：118
期号：33
DOI：10.1073/pnas.2102034118
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Nociceptors are sensory neurons that detect changes in the body’s internal and external milieu. Although occupying a primary role in signaling these changes to the nervous system, nociceptors also initiate neurogenic inflammation by sending antidromic signals back into the tissue. Because HMGB1 is a well-characterized endogenous mediator, which stimulates inflammation and is expressed by neurons, we reasoned HMGB1 release may be an important component of neurogenic inflammation. Here, by combining optogenetics, neuronal-specific ablation, nerve-injury, and inflammatory disease models, with direct assessment of inflammation and neuropathic pain, we show that nociceptor HMGB1 is required for an inflammatory response. These results provide direct evidence that nociceptor-related pain and inflammation can be prevented by targeting HMGB1.
Inflammation, the body’s primary defensive response system to injury and infection, is triggered by molecular signatures of microbes and tissue injury. These molecules also stimulate specialized sensory neurons, termed nociceptors. Activation of nociceptors mediates inflammation through antidromic release of neuropeptides into infected or injured tissue, producing neurogenic inflammation. Because HMGB1 is an important inflammatory mediator that is synthesized by neurons, we reasoned nociceptor release of HMGB1 might be a component of the neuroinflammatory response. In support of this possibility, we show here that transgenic nociceptors expressing channelrhodopsin-2 (ChR2) directly release HMGB1 in response to light stimulation. Additionally, HMGB1 expression in neurons was silenced by crossing synapsin-Cre (Syn-Cre) mice with floxed HMGB1 mice (HMGB1
f/f). When these mice undergo sciatic nerve injury to activate neurogenic inflammation, they are protected from the development of cutaneous inflammation and allodynia as compared to wild-type controls. Syn-Cre/HMGB1
fl/fl mice subjected to experimental collagen antibody–induced arthritis, a disease model in which nociceptor-dependent inflammation plays a significant pathological role, are protected from the development of allodynia and joint inflammation. Thus, nociceptor HMGB1 is required to mediate pain and inflammation during sciatic nerve injury and collagen antibody–induced arthritis.
