BACKGROUND

The role of the IL6 family members in organ fibrosis, including renal interstitial fibrosis (TIF), has been widely explored. However, few studies have ever simultaneously examined them in the same cohort of patients. Besides, the role of leukemia inhibitory factor (LIF) in TIF remains unclear.

METHODS

RNA-seq data of kidney biopsies from chronic kidney disease (CKD) patients, in both public databases and our assays, were used to analyze transcript levels of IL6 family members. Two TIF mouse models, the unilateral ureteral obstruction (UUO) and the ischemia reperfusion injury (IRI), were employed to validate the finding. To assess the role of LIF in vivo, short hairpin RNA, lenti-GFP-LIF was used to knockdown LIF receptor (LIFR), overexpress LIF, respectively. LIF-neutralizing antibody was used in therapeutic studies. Whether urinary LIF could be used as a promising predictor for CKD progression was investigated in a prospective observation patient cohort.

FINDINGS

Among IL6 family members, LIF is the most upregulated one in both human and mouse renal fibrotic lesions. The mRNA level of LIF negatively correlated with eGFR with the strongest correlation and the smallest P value. Baseline urinary concentrations of LIF in CKD patients predict the risk of CKD progression to end-stage kidney disease by Kaplan-Meier analysis. In mouse TIF models, knockdown of LIFR alleviated TIF; conversely, overexpressing LIF exacerbated TIF. Most encouragingly, visible efficacy against TIF was observed by administering LIF-neutralizing antibodies to mice. Mechanistically, LIF-LIFR-EGR1 axis and Sonic Hedgehog signaling formed a vicious cycle between fibroblasts and proximal tubular cells to augment LIF expression and promote the pro-fibrotic response via ERK and STAT3 activation.

INTERPRETATION

This study discovered that LIF is a noninvasive biomarker for the progression of CKD and a potential therapeutic target of TIF.

FUNDINGS

Stated in the Acknowledgements section of the manuscript.