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Inflammation and fibrosis play an important pathophysiological role in chronic kidney disease (CKD), with pro-inflammatory mediators and leukocytes promoting organ damage with subsequent fibrosis. Since chemokines are the main regulators of leukocyte chemotaxis and tissue inflammation, we performed systemic chemokine profiling in early CKD in mice. This revealed (C-C motif) ligands 6 and 9 (CCL6 and CCL9) as the most upregulated chemokines, with significantly higher levels of both chemokines in blood (CCL6: 3–4 fold; CCL9: 3–5 fold) as well as kidney as confirmed by Enzyme-linked Immunosorbent Assay (ELISA) in two additional CKD models. Chemokine treatment in a mouse model of early adenine-induced CKD almost completely abolished the CKD-induced infiltration of macrophages and myeloid cells in the kidney without impact on circulating leukocyte numbers. The other way around, especially CCL9-blockade aggravated monocyte and macrophage accumulation in kidney during CKD development, without impact on the ratio of M1-to-M2 macrophages. In parallel, CCL9-blockade raised serum creatinine and urea levels as readouts of kidney dysfunction. It also exacerbated CKD-induced expression of collagen (3.2-fold) and the pro-inflammatory chemokines CCL2 (1.8-fold) and CCL3 (2.1-fold) in kidney. Altogether, this study reveals for the first time that chemokines CCL6 and CCL9 are upregulated early in experimental CKD, with CCL9-blockade during CKD initiation enhancing kidney inflammation and fibrosis.

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Background and Aims Chronic Kidney Disease (CKD) is causing serious cardiovascular diseases. Creatinine quantification and eGFR estimation are suboptimal approaches for the diagnosis of CKD, especially at early stages. Therefore, there is a strong need for identification of mediators for CKD diagnosis and prediction of disease progression. In this study we follow a cohort of renal healthy patients (controls) and CKD patients (cases) for two years, defining three time points (baseline, after 12 months and after 24 months), with the aim of identifying and characterizing mediators of disease which could be an indication for the development and progression of CKD and its outcome. Method By the employment of liquid chromatography-mass spectrometry (LC-MS) we analyzed the plasma samples from the patients and identified the mediators1 : lysine (K), an angio-associated migratory cell protein (AAMP) peptide and an amiloride-sensitive oxidase (AOC1) peptide, which were consistently and differentially expressed in cases and controls at all time points. Correlation analyses between the mediators and clinical markers were performed using the software R-Studio (RStudio Team (2020). RStudio: Integrated Development for R. RStudio, PBC, Boston, MA URL http://www.rstudio.com/). The AAMP peptide was subsequently tested in a fibroblasts cells culture to investigate whether it was an inflammation inducer, its action was investigated at four different concentrations (0.1nM, 1nM, 100nM, 1000nM). Cells were stimulated for 48h and relative expression of two inflammation markers (CCL2 and IL6) was measured through PCR. Results Correlation analyses revealed that the AAMP peptide showed from modest to strong relations with clinical markers such as creatinine, hemoglobin, blood urea nitrogen, homocysteine, fibrinogen and parathyroid hormone. Results showed that the peptide after 48h of stimulation did not cause an increase in the expression of gene CCL2 at any concentration, but caused a strong increase of gene IL6 (interleukin-6), a cytokine promoting inflammation and B cells maturation. Conclusion In conclusion, angio-associated migratory cell peptide, might be involved in CKD by inducing inflammation and driving the development of cardiovascular consequences such as atherosclerosis. Acknowledgments This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 764474.