ABSTRACT
Japanese encephalitis (JE) is neuroinflammation characterized by uncontrolled infiltration of peripheral leukocytes into the central nervous system (CNS). We previously demonstrated exacerbation of JE following CD11c(hi) dendritic cell (DC) ablation in CD11c-DTR transgenic mice. Moreover, CD11c(hi) DC ablation led to abnormal differentiation of CD11b⁺Ly-6C(hi) monocytes and enhanced permeability of the blood-brain barrier (BBB), resulting in promoting the progression of JE. Here, we examined changes in lymphoid and myeloid-derived leukocyte subpopulations associated with pro- and anti-inflammation during JE progression. The analyses of this study focused on regulatory CD4⁺Foxp3⁺ regulatory T cells (Tregs), IL-17⁺CD4⁺ Th17 cells, and CD11b⁺Ly-6C(hi) and Ly-6C(lo) monocytes. CD11c(hi) DC ablation resulted in the accumulation of IL-17⁺CD4⁺ Th17 cells in the CNS, thereby leading to lower ratio of Tregs to Th17 cells. This result was corroborated by the higher expression levels of IL-17 and RORγT in CD4⁺ T cells from the brains of CD11c(hi) DC-ablated mice. In addition, CD11c(hi) DC-ablated mice showed higher frequency and total number of inflammatory CD11b⁺Ly-6C(hi) monocytes, whereas CD11b⁺Ly-6C(lo) monocytes were detected with lower frequency and total number in CD11c(hi) DC-ablated mice. Furthermore, CD11c(hi) DC ablation altered the phenotype and function of CD11b⁺Ly-6C(lo) monocytes, resulting in lower levels of activation marker and anti-inflammatory cytokine (IL-10 and TGF-β) expression. Collectively, these results indicate that CD11c(hi) DC ablation caused an imbalance in CD4⁺ Th17/Treg cells and CD11b⁺Ly-6C(hi)/Ly-6C(lo) monocytes in the lymphoid tissue and CNS during JE progression. This imbalanced orchestration of pro- and anti-inflammatory leukocytes following CD11c(hi) DC ablation may contribute to the exacerbation of JE.
Subject(s)
Animals , Humans , Mice , Asian People , Blood-Brain Barrier , Brain , Central Nervous System , Dendritic Cells , Encephalitis, Japanese , Interleukin-17 , Leukocytes , Lymphoid Tissue , Mice, Transgenic , Monocytes , Permeability , Phenotype , T-Lymphocytes , T-Lymphocytes, Regulatory , Th17 CellsABSTRACT
Cholera toxin, which has been frequently used as mucosal adjuvant, leads to an irreversible activation of adenylyl cyclase, thereby accumulating cAMP in target cells. Here, it was assumed that beta2-adrenergic agonist salbutamol may have modulatory functions of immunity induced by DNA vaccine, since beta2-adrenergic agonists induce a temporary cAMP accumulation. To test this assumption, the present study evaluated the modulatory functions of salbutamol co-administered with DNA vaccine expressing gB of herpes simplex virus (HSV) via intranasal (i.n.) route. We found that the i.n. co-administration of salbutamol enhanced gB-specific IgG and IgA responses in both systemic and mucosal tissues, but optimal dosages of co-administered salbutamol were required to induce maximal immune responses. Moreover, the mucosal co-delivery of salbutamol with HSV DNA vaccine induced Th2-biased immunity against HSV antigen, as evidenced by IgG isotypes and Th1/Th2-type cytokine production. The enhanced immune responses caused by co-administration of salbutamol provided effective and rapid responses to HSV mucosal challenge, thereby conferring prolonged survival and reduced inflammation against viral infection. Therefore, these results suggest that salbutamol may be an attractive adjuvant for mucosal genetic transfer of DNA vaccine.