Interferon γ Derived from CD4+ T Cells Is Sufficient to Mediate T Helper Cell Type 1 Development

Interferon γ (IFN-γ) has been implicated in T helper type 1 (Th1) cell development through its ability to optimize interleukin 12 (IL-12) production from macrophages and IL-12 receptor expression on activated T cells. Various systems have suggested a role for IFN-γ derived from the innate immune system, particularly natural killer (NK) cells, in mediating Th1 differentiation in vivo. We tested this requirement by reconstituting T cell and IFN-γ doubly deficient mice with wild-type CD4⁺ T cells and challenging the mice with pathogens that elicited either minimal or robust IL-12 in vivo (Leishmania major or Listeria monocytogenes, respectively). Th1 cells developed under both conditions, and this was unaffected by the presence or absence of IFN-γ in non-T cells. Reconstitution with IFN-γ–deficient CD4⁺ T cells could not reestablish control over L. major, even in the presence of IFN-γ from the NK compartment. These data demonstrate that activated T cells can maintain responsiveness to IL-12 through elaboration of endogenous IFN-γ without requirement for an exogenous source of this cytokine.     

Spinal macrophage migration inhibitory factor contributes to the pathogenesis of inflammatory hyperalgesia in rats

Pro-inflammatory cytokine production after nociceptive stimuli is pivotal for hyperalgesia. As macrophage migration inhibitory factor (MIF), a pleiotropic cytokine produced mainly by nonneuronal tissue, has been involved in the regulation of neuronal functions, herein we examined the role for MIF in formalin-induced inflammatory pain model. MIF critically contributed to nociceptive behaviors following formalin injection. Specifically, spinal administration of a MIF inhibitor (ISO-1) prevented and reversed flinching responses in rats. Further examination showed that levels of both MIF and the MIF receptor CD74 were substantially increased within the ipsilateral spinal cord dorsal horn after formalin administration. Mechanistic studies revealed that MIF upregulated the expression of the spinal NMDA receptor subunit NR2B via the MAPK signaling pathway. Moreover, microglial cells were found to be the major source of spinal MIF after formalin administration by fluorescence colocalization. These data highlight spinal MIF plays a critical role in the pathogenesis of formalin-induced inflammatory pain and suggest MIF may be a potential target for therapy of such pathological condition.     

Current and future therapeutic strategies for functional repair of spinal cord injury

Spinal cord injury (SCI) is one of the major disabilities dealt with in clinical rehabilitation settings and is multifactorial in that the patients suffer from motor and sensory impairments as well as many other complications throughout their lifetimes. Many clinical trials have been documented during the last two decades to restore damaged spinal cords. However, only a few pharmacological therapies used in clinical settings which still have only limited effects on the regeneration and functional recovery. This review presents recent clinical trials and recent advances in the development of strategies to restore locomotion after SCI. Several approaches toward functional recovery in SCI succeeded in acute and subacute phases in animal models.However, effective strategies against chronic phase of SCI have not been established yet. The strategy aiming to inhibit single molecule sometimes shows controversial results. In SCI, a lot of players participate in motor and sensory dysfunctions. Therefore, sufficient functional recovery may be achieved by regulating multiple targets. Regrowth of tracts connecting the brain and spinal cord, and axonal sprouting of propriospinal interneurons are fundamentally important for neuronal network working. In addition, remyelination, protection of neuronal death, inhibition of inflammation, and upregulation of beneficial influence of astrocytes are also quite crucial to supporting the axonal refining. Combination of several strategies might be useful as practical therapy. Several compounds such as a Sema3A inhibitor, estrogen, withanoside IV and their relating compounds or other neurotrophic factor-mimicking agents may be candidates for useful SCI therapeutic drugs since those have multi-effects on damaged spinal cord.