The wingless-related MMTV integration site (WNT)5A has pro-inflammatory effects and induces insulin resistance in mice. The secreted frizzled-related protein 5 (SFRP5) blocks the deleterious effects of WNT5A in mice. In humans, the interaction of WNT5A and SFRP5 in the pathogenesis of type 2 diabetes is almost unknown. Therefore, the aim of this study was to characterize the interplay of WNT5A and SFRP5 in glucose metabolism and inflammation in human hepatocytes. We treated the human HepaRG cell line without or with (i) 5 ng/ml WNT5A, (ii) 5000 ng/ml SFRP5 as well as (iii) 5 ng/ml WNT5A and 5000 ng/ml SFRP5 for 24 h. The mRNA levels of key enzymes of the gluconeogenesis were measured using real-time PCR. We analyzed 92 inflammatory proteins in the supernatant using the OLINK inflammation panel. Total and phosphorylated protein content of markers of inflammatory pathways were analysed using Western blotting. WNT5A increased mRNA levels of phosphoenolpyruvate carboxykinase (PCK)2 and glucose-6-phosphatase catalytic subunit (G6PC) by 50% and 196% compared to control (p<0.05). Interestingly, the co-treatment with SFRP5 decreased PCK2 and G6PC mRNA by 36% and 48% compared to control (p<0.05). In addition, WNT5A reduced the secretion of protein levels of 23 pro-inflammatory proteins in the supernatant on average by 56% compared to control (p<0.05). Most of these proteins were chemokines (e.g., CXCL5, CCL2) and cytokines (e.g., IL-6, IL-18). WNT5A also decreased the phosphorylation level of NF-κB by 39% (p<0.01). The co-treatment with SFRP5 led to a secretion profile similar to control.
In conclusion, contrary to mouse models, WNT5A has anti-inflammatory properties in human HepaRG which might be mediated by inactivation of the NF-κB signaling pathway. Nevertheless, WNT5A adversely affects the expression of gluconeogenic enzymes. SFRP5 antagonizes both beneficial and harmful hepatic effects of WNT5A.
M. Carstensen-Kirberg: None. C. Niersmann: None. K. Roehrig: None. M. Roden: Speaker's Bureau; Self; Boehringer Ingelheim GmbH. Research Support; Self; Boehringer Ingelheim GmbH. Consultant; Self; Poxel SA. Research Support; Self; Danone Nutricia Early Life Nutrition, GlaxoSmithKline plc., Nutricia Advanced Medical Nutrition, Sanofi. C. Herder: Other Relationship; Self; Sanofi, Eli Lilly and Company.