Current experimental evidence does not support macrophage-to-myofibroblast transition as a universal or quantitatively dominant source of effector cells in renal interstitial fibrosis, according to a review published in Cell Biology and Toxicology. While myofibroblasts are recognized as the principal effector cells driving renal interstitial fibrosis, scientific debate persists regarding the relative contribution of different proposed cellular sources. Historically, the phenomenon of macrophage-to-myofibroblast transition has been inferred from cellular marker co-expression studies, single-recombinase lineage tracing, and functional perturbation models. However, rigorous dual-recombinase lineage tracing with high specificity in unilateral ureteral obstruction models identified resident fibroblasts as the predominant cellular origin of myofibroblasts, detecting no appreciable contribution from macrophage lineages.
To resolve these longstanding discrepancies in experimental findings, the authors distinguish three distinct evidentiary categories: lineage-confirmed macrophage-to-myofibroblast transition, transition-like macrophage remodeling, and broader profibrotic macrophage activation. The researchers conduct a detailed comparative evaluation across multiple investigative approaches, contrasting marker co-expression phenotyping with single-recombinase and dual-recombinase lineage-tracing systems. Their analysis further incorporates data from advanced single-cell omics, spatial omics technologies, and controlled in vitro cell induction protocols to evaluate how cellular identities are defined across different experimental settings.
In addition to evaluating lineage-tracing methodologies, the review organizes candidate molecular mechanisms into an explicit causal signaling hierarchy centered on transforming growth factor-beta 1 and Smad3, acting upstream of Src and Pou4f1 pathways. The authors evaluate this regulatory axis within the broader framework of disease context and its therapeutic implications for kidney scarring.
The authors conclude that existing scientific evidence does not support macrophage-to-myofibroblast transition as a quantitatively major contributor to renal interstitial fibrosis. Furthermore, the possibility that a small population of transition-like macrophages could exert disproportionate local pathological effects remains an unproven, testable hypothesis rather than an established conclusion. To resolve the ongoing debate, the review outlines specific falsifiable experiments designed to establish precise criteria defining where, when, and by what rigorous experimental standards macrophage-derived fibrogenic states can be demonstrated in renal interstitial fibrosis.
Subject of Research: Macrophage-to-myofibroblast transition in renal interstitial fibrosis
Article Title: Macrophage-to-myofibroblast transition in renal fibrosis: controversy, context dependence, and therapeutic implications
Article References: Chen, G., Xiao, C., Wang, Y., & Yang, K. (2026). Macrophage-to-myofibroblast transition in renal fibrosis: controversy, context dependence, and therapeutic implications. Cell Biology and Toxicology. https://doi.org/10.1007/s10565-026-10301-0
Image Credits: AI Generated
DOI: 10.1007/s10565-026-10301-0
Keywords: renal interstitial fibrosis, myofibroblasts, macrophage-to-myofibroblast transition, lineage tracing, kidney disease, dual-recombinase tracing, fibroblasts, Cell Biology and Toxicology, Macrophage-to-myofibroblast, transition, renal, fibrosis
News Source: Drew Townsend. (November 5, 2026). Review Examines Evidence for Macrophage Transition in Renal Interstitial Fibrosis. Scienmag.
