Rat CX3C-chemokine/Fractalkine ELISA Kit

Fructose, the most important functional food additive from the last century, has been widely used in industry, agriculture, light industry, food and medicine. With the improvement of people's living standard and economic level, excess intake of fructose results in metabolic symptoms, including hyperleptinemia, insulin resistance and neuroinflammation is causing high risk of chronic kidney disease development in humans and animals. However, the underlying molecular mechanism of renal injury is still not fully understood, and the development of effective drugs and treatments are delayed. Hence, we investigated the role of crosstalk of CX3CL1-CX3CR1 axis and nuclear factor-B (NF-B) signaling pathway in the development of renal injury. CX3CL1-knock-out C57BL/6 mice were constructed and used to analyze the influence of CX3CL1-related signaling pathways on kidney injury of wild-type (WT) mice and CXECR1 deficiency mice, which were administrated with 30% fructose water. Western blotting, quantitative RT-PCR (qRT-PCR), immunohistochemistry, ELISA, flow cytometry and biochemical indicator analysis were used to determine the levels of renal injury and key signaling pathway associated with renal damage. The results indicated that administration of high fructose intake can cause typical renal inflammatory responses in serum and tissues. Fructose enhances the CX3CL1-CX3CR1 axis and NF-B activation, and promotes crosstalk of CX3CL1-CX3CR1 and NF-B pathways. The phosphorylated AKT could be significantly activated in fructose-induced renal injury via CX3CL1-CX3CR1 axis. CX3CR1 expression between WT and CX3CR1(-/-) mice were evaluated to establish their relationship with injury. Our results indicated that CX3CR1 may be the central and major indicator in the process of renal injury, which mediate AKT pathway and further enhance the NF-B activation. These findings demonstrated that crosstalk of CX3CL1-CX3CR1 axis and NF-B signaling pathway play a direct role in fructose-induced kidney injury. Inhibition of CX3CL1-CX3CR1 pathway may suppress renal-related diseases. It may be a potential treatment choice for the clinical diagnoses and treatment in the future.

Neurodegeneration in glaucoma results in decline and loss of retinal ganglion cells (RGCs), and is associated with activation of myeloid cells such as microglia and macrophages. The chemokine fractalkine (FKN or Cx3cl1) mediates communication from neurons to myeloid cells. Signaling through its receptor Cx3cr1 has been implicated in multiple neurodegenerative diseases, but the effects on neuronal pathology are variable. Since it is unknown how FKN-mediated crosstalk influences RGC degeneration in glaucoma, we assessed this in a chronic mouse model, DBA/2J. We analyzed a DBA/2J substrain deficient in Cx3cr1, and compared compartmentalized RGC degeneration and myeloid cell responses to those in standard DBA/2J mice. We found that loss of FKN signaling exacerbates axon transport dysfunction, an early event in neurodegeneration, with a significant increase in RGCs with somal accumulation of the axonal protein phosphorylated neurofilament, and reduced retinal expression of genes involved in axon transport, Kif1b, and Atp8a2. There was no change in the loss of Brn3-positive RGCs, and no difference in the extent of damage to the proximal optic nerve, suggesting that the loss of fractalkine signaling primarily affects axon transport. Since Cx3cr1 is specifically expressed in myeloid cells, we assessed changes in retinal microglial number and activation, changes in gene expression, and the extent of macrophage infiltration. We found that loss of fractalkine signaling led to innate immune changes within the retina, including increased infiltration of peripheral macrophages and upregulated nitric oxide synthase-2 (Nos-2) expression in myeloid cells, which contributes to the production of NO and can promote axon transport deficits. In contrast, resident retinal microglia appeared unchanged either in number, morphology, or expression of the myeloid activation marker ionized calcium binding adaptor molecule 1 (Iba1). There was also no significant increase in the proinflammatory gene interleukin 1 beta (Il1 beta). We conclude that loss of fractalkine signaling causes a selective worsening of axon transport dysfunction in RGCs, which is linked to enhanced Nos-2 expression in myeloid cells. Our findings suggest that distinct mechanisms may contribute to different aspects of RGC decline in glaucoma, with axonal transport selectively altered after loss of Cx3cr1 in microglia and/or macrophages.