The synergy in cytokine production through MyD88-TRIF pathways is co-ordinated with ERK phosphorylation in macrophages.

Although specific single Toll-like receptor (TLR) ligands are known to drive the development of Th1 or Th2 immunity, the outcome of different combinations of TLR ligands on innate immunity is not well defined. Spatiotemporal dynamics are critical in determining the specificity of the immune response, but the mechanisms underlying combinatorial TLR stimulation remain unclear. Here, we tested pairwise combinations of TLR ligands separated by different time intervals for their effect on cytokine production in macrophages. We observed that stimulation via a combination of MyD88- and TRIF-utilizing adaptors leads to a highly synergistic cytokine response. On a timescale of 4-24 h, macrophages pretreated with poly(I:C) (TLR3 ligand) are cross-primed to a second stimulation with R848 (TLR7 ligand) and vice versa, and each condition exhibits different optimal time windows of synergistic response for each cytokine. We show that the synergy resulting from combinatorial stimuli (poly(I:C) and R848 is also regulated by the order and dosage of the TLR agonists. Secondary response genes, which depend on new protein synthesis for transcription, show greater synergy than primary response genes, and such enhancement is abolished when new protein synthesis is inhibited. Synergistic cytokine production appears concordant with sustained ERK phosphorylation, suggesting that the de novo factors act via inhibition of ERK dephosphorylation, for example, by the downregulation of dual specificity phosphatase 6. Taken together, our findings illustrate a checkpoint in the innate immune system, where the synchronization of timing of both MyD88 and TRIF pathways is required for a maximal cytokine response and potential memory effect in macrophages.

Urine sVCAM-1 and sICAM-1 levels are elevated in lupus nephritis.

AIM: We sought to evaluate the relationship of urine levels of soluble cellular adhesion molecules sVCAM-1 (vascular) and sICAM-1 (intercellular) in systemic lupus erythematosus (SLE) patients with or without lupus nephritis, and to explore their correlation with renal disease activity. METHODS: Paired serum and urine samples of 121 Asian SLE patients, and urine samples of 19 normal healthy controls were collected. Demographic data, disease activity and damage scores, and selected laboratory parameters, including levels of anti-double stranded DNA antibody, complements C3, C4, and creatinine were captured. Renal disease activity was scored with renal SLE Activity Measure revised (rSLAM-R). Serum and urine sVCAM-1 and sICAM-1 levels were assayed by enzyme-linked immunosorbent assay. RESULTS: Urinary sVCAM-1 and sICAM-1 were elevated in SLE patients compared to controls. Significantly higher levels of urine sVCAM-1 found in patients with active lupus nephritis correlated with rSLAM-R. In addtion, significantly more patients with active lupus nephritis had detectable levels of urine sICAM-1, but no correlation with renal activity was observed. CONCLUSION: Urinary sVCAM-1 may serve as a potential biomarker for early diagnosis of lupus nephritis as levels correlated with even mild abnormalities of urine sediment. In addition, both urine sVCAM-1 and sICAM-1 levels may be useful in identifying patients at risk of lupus nephritis.