Salt suppresses IFNγ inducible chemokines through the IFNγ-JAK1-STAT1 signaling pathway in proximal tubular cells

• Published in: Scientific reports 2017-04, Vol.7 (1), p.46580, Article 46580
• Main Authors: Arai, Yohei, Takahashi, Daiei, Asano, Kenichi, Tanaka, Masato, Oda, Mayumi, Ko, Shigeru B. H., Ko, Minoru S. H., Mandai, Shintaro, Nomura, Naohiro, Rai, Tatemitsu, Uchida, Shinichi, Sohara, Eisei
• Format: Article
• Language: English
• Subjects: 631/443/272; 631/80/86; 64/60; 82/1; Animals; Antiviral Agents - pharmacology; Cell Line; Chemokines - genetics; Chemokines - metabolism; Epithelial Cells - drug effects; Epithelial Cells - metabolism; Humanities and Social Sciences; Humans; Interferon gamma Receptor; Interferon-gamma - metabolism; Interferon-gamma - pharmacology; Janus Kinase 1 - metabolism; Kidney Tubules, Proximal - cytology; Mice, Inbred C57BL; Mice, Knockout; multidisciplinary; Receptors, Interferon - genetics; Receptors, Interferon - metabolism; Science; Signal Transduction - drug effects; Signal Transduction - genetics; Sodium Chloride - pharmacology; STAT1 Transcription Factor - metabolism; Transcriptome - drug effects; Transcriptome - genetics
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep46580

The mechanisms of immunoactivation by salt are now becoming clearer. However, those of immunosuppression remain unknown. Since clinical evidence indicates that salt protects proximal tubules from injury, we investigated mechanisms responsible for salt causing immunosuppression in proximal tubules. We focused on cytokine-related gene expression profiles in kidneys of mice fed a high salt diet using microarray analysis and found that both an interferon gamma (IFNγ) inducible chemokine, chemokine (C-X-C motif) ligand 9 (CXCL9), and receptor, CXCR3, were suppressed. We further revealed that a high salt concentration suppressed IFNγ inducible chemokines in HK2 proximal tubular cells. Finally, we demonstrated that a high salt concentration decreased IFNGR1 expression in the basolateral membrane of HK2 cells, leading to decreased phosphorylation of activation sites of Janus kinase 1 (JAK1) and Signal Transducers and Activator of Transcription 1 (STAT1), activators of chemokines. JAK inhibitor canceled the effect of a high salt concentration on STAT1 and chemokines, indicating that the JAK1-STAT1 signaling pathway is essential for this mechanism. In conclusion, a high salt concentration suppresses IFNγ-JAK1-STAT1 signaling pathways and chemokine expressions in proximal tubules. This finding may explain how salt ameliorates proximal tubular injury and offer a new insight into the linkage between salt and immunity.