van Raalte, D. | Search bioRxiv

bioRxiv2025

NNMT promotes tubular senescence and fibrosis in chronic kidney disease

Chronic kidney disease (CKD) is a major global health issue, projected to become the fifth leading cause of mortality by 2040. Renal tubular cell senescence is a key driver of kidney fibrosis, the final manifestation of CKD. However, current treatment strategies, do not target senescent cells, as the underlying mechanisms driving this dysfunctional phenotype remain poorly described. Here, we identify nicotinamide-N-methyltransferase (NNMT), as a critical mediator of tubular senescence and fibrosis in CKD. Using human RNAseq profiles of CKD, we show that NNMT expression in the renal tubulointerstitium is strongly associated with CKD pathology and transcriptional signatures of cellular senescence. In human diabetic kidney disease biopsies, NNMT levels correlate with the senescence marker p21, kidney function decline, and fibrosis. Spatial transcriptomics further highlights that NNMT-positive tubules are senescent, fibrotic, and surrounded by a pro-inflammatory microenvironment. Preclinical models of early-stage CKD, show upregulation of NNMT and association with senescence. Overexpression of NNMT in TGF-{beta}-stimulated tubular epithelial cells promotes senescence and partial epithelial-to-mesenchymal transition (EMT), while inhibition of NNMT in kidney cells and organoids is protective. Altogether, we identify NNMT as a novel therapeutic target in the early stages of CKD with the potential to reduce tubular senescence, fibrosis and significantly slow disease progression.

cell biology↗

bioRxiv2022

High fat diet changes bacterial signatures in the murine pancreas

Hyperglycemia is caused by failure of pancreatic beta cells. Beta-cell inflammation contributes to beta-cell dysfunction, however (primary) immunogenic triggers are in large unknown. The gut microbiota is one potential source of pro-inflammatory molecules. A high-fat diet treatment increases pro-inflammatory bacteria in the gut microbiome, parts of which could migrate to the pancreatic beta-cell. In the present study, the bacterial DNA signature in the pancreas and intestine of C57BL6/J mice was analyzed. Mice were fed a high-fat diet (60% kcal fat) or a regular chow diet for 12 weeks. We took several precautions to avoid and map contamination. The gut microbiota was affected by high-fat diet as following: We observed several common intestinal ASVs in the pancreatic tissue. Although the pancreatic ASVs do not correlate exactly with the gut ASVs, our data implicate that the pancreas contains bacterial DNA and that this signature is altered in high-fat diet fed mice (PERMONOVA, p = 0.037; betadisper, p=0.029). Gut derived bacterial DNA might end up in the pancreas at some point in time. Hence, this work supports the concept of translocation of bacterial DNA to the pancreas, which might contribute to inflammation and dysfunction of pancreatic beta-cells.

microbiology↗