PMC:4136538 / 2064-4935 JSONTXT

{"project":"2_test","denotations":[{"id":"25143871-21764514-63946004","span":{"begin":147,"end":148},"obj":"21764514"},{"id":"25143871-21764514-63946004","span":{"begin":147,"end":148},"obj":"21764514"},{"id":"25143871-14623723-63946005","span":{"begin":187,"end":188},"obj":"14623723"},{"id":"25143871-14623723-63946005","span":{"begin":187,"end":188},"obj":"14623723"},{"id":"25143871-21496480-63946006","span":{"begin":400,"end":401},"obj":"21496480"},{"id":"25143871-21496480-63946006","span":{"begin":400,"end":401},"obj":"21496480"},{"id":"25143871-18196515-63946007","span":{"begin":649,"end":650},"obj":"18196515"},{"id":"25143871-18196515-63946007","span":{"begin":649,"end":650},"obj":"18196515"},{"id":"25143871-20192806-63946008","span":{"begin":1055,"end":1056},"obj":"20192806"},{"id":"25143871-20192806-63946008","span":{"begin":1055,"end":1056},"obj":"20192806"},{"id":"25143871-15541898-63946009","span":{"begin":1541,"end":1542},"obj":"15541898"},{"id":"25143871-15541898-63946009","span":{"begin":1541,"end":1542},"obj":"15541898"},{"id":"25143871-21295862-63946010","span":{"begin":1912,"end":1913},"obj":"21295862"},{"id":"25143871-21295862-63946010","span":{"begin":1912,"end":1913},"obj":"21295862"},{"id":"25143871-19923276-63946011","span":{"begin":1914,"end":1915},"obj":"19923276"},{"id":"25143871-19923276-63946011","span":{"begin":1914,"end":1915},"obj":"19923276"},{"id":"25143871-16674943-63946012","span":{"begin":2139,"end":2140},"obj":"16674943"},{"id":"25143871-16674943-63946012","span":{"begin":2139,"end":2140},"obj":"16674943"},{"id":"25143871-20889388-63946012","span":{"begin":2139,"end":2140},"obj":"20889388"},{"id":"25143871-20889388-63946012","span":{"begin":2139,"end":2140},"obj":"20889388"},{"id":"25143871-21316418-63946012","span":{"begin":2139,"end":2140},"obj":"21316418"},{"id":"25143871-21316418-63946012","span":{"begin":2139,"end":2140},"obj":"21316418"},{"id":"T74977","span":{"begin":147,"end":148},"obj":"21764514"},{"id":"T89383","span":{"begin":147,"end":148},"obj":"21764514"},{"id":"T62205","span":{"begin":187,"end":188},"obj":"14623723"},{"id":"T5782","span":{"begin":187,"end":188},"obj":"14623723"},{"id":"T14531","span":{"begin":400,"end":401},"obj":"21496480"},{"id":"T87200","span":{"begin":400,"end":401},"obj":"21496480"},{"id":"T396","span":{"begin":649,"end":650},"obj":"18196515"},{"id":"T93531","span":{"begin":649,"end":650},"obj":"18196515"},{"id":"T31693","span":{"begin":1055,"end":1056},"obj":"20192806"},{"id":"T91597","span":{"begin":1055,"end":1056},"obj":"20192806"},{"id":"T33817","span":{"begin":1541,"end":1542},"obj":"15541898"},{"id":"T6846","span":{"begin":1541,"end":1542},"obj":"15541898"},{"id":"T83887","span":{"begin":1912,"end":1913},"obj":"21295862"},{"id":"T5540","span":{"begin":1912,"end":1913},"obj":"21295862"},{"id":"T48831","span":{"begin":1914,"end":1915},"obj":"19923276"},{"id":"T78193","span":{"begin":1914,"end":1915},"obj":"19923276"},{"id":"T27058","span":{"begin":2139,"end":2140},"obj":"16674943"},{"id":"T47949","span":{"begin":2139,"end":2140},"obj":"16674943"},{"id":"T69382","span":{"begin":2139,"end":2140},"obj":"20889388"},{"id":"T12980","span":{"begin":2139,"end":2140},"obj":"20889388"},{"id":"T25888","span":{"begin":2139,"end":2140},"obj":"21316418"},{"id":"T83084","span":{"begin":2139,"end":2140},"obj":"21316418"}],"text":"As one of the most devastating kinds of chronic pain, neuropathic pain, defined as pain caused by a lesion or disease of the somatosensory system [1], is a great challenge to physicians [2]. Decades of investigation using pre-clinical models has provided ample evidence of the contribution of the adaptive immune system (lymphocyte-mediated immune responses), to the development of neuropathic pain [3]. Specifically, using a well-established murine model, spinal nerve L5 transection (L5Tx), our laboratory has demonstrated that spinal cord-infiltrating CD4+ T lymphocytes contribute to the maintenance of L5Tx-induced mechanical hypersensitivity [4], indicating the involvement of helper CD4+ T lymphocyte-mediated immune responses in neuropathic pain. It is well known that helper CD4+ T lymphocytes can be classified into several functional subtypes, including type 1 (Th1, mediating primarily cell-mediated immunity), type 2 (Th2, mediating primarily humoral responses), and type 17 (Th17, mediating primarily inflammatory responses) helper T cells [5]. Each subtype of helper T cells has a distinct transcription factor and cytokine profile that drives the downstream responses they mediate. Previously, a limited number of studies that used indirect approaches suggested that Th1 is the dominant helper T cell subtype in mediating the development of neuropathic pain. First, Moalem et al. demonstrated that the passive transfer of in vitro maintained Th1, but not Th2, cells promoted nerve injury-induced behavioral hypersensitivity [6]. Others have subsequently shown the close association between increased spinal cord interferon IFN-γ (the signature cytokine produced by Th1 cells) and behavioral hypersensitivity, as well as an association between increased interleukin (IL)-4 (the signature cytokine produced by Th2 cells) expression and a reduction in nerve injury-induced sensory hypersensitivity [7,8]. More recently, the involvement of IL-17 (the signature cytokine produced by Th17 cells) in the development of peripheral nerve injury-induced neuropathic pain was described, suggesting a role of Th17 in neuropathic pain [9–11]. However, there have been no studies that directly examined the phenotype(s) of the infiltrating CD4+ T lymphocytes following peripheral nerve injury, which may in part be due to the technical difficulty of isolating the small number of lumbar spinal cord-infiltrating T cells. Thus, in the current study, we directly evaluated spinal cord-infiltrating CD4+ T lymphocytes based on their intracellular expression profiles of subtype-specific transcription factors and cytokines via flow cytometric analysis using the L5Tx model of neuropathic pain. As we did not detect significant changes in IL-17 expression in the lumbar spinal cord post-L5Tx in preliminary studies, we focused our investigation on the Th1 and Th2 subtypes."}