Intracellular complement Factor B couples inflammatory sensing to metabolism, chromatin regulation and maladaptive tissue repair
- 1National Institutes of Health
Abstract
Inflammatory signals are broadly conserved, yet how tissue context converts them into programs of recovery or maladaptive repair remains unclear. Using kidney injury as a model of inflammation-to-repair transitions, we identify an injury-induced proximal-tubule complement program in which cell-intrinsic complement proteins are repurposed across subcellular compartments to couple inflammation to metabolic and chromatin regulation and promote maladaptive fibrotic remodeling. Mechanistically, myeloid-derived IL-1b; signals through IL-1R1 on injured tubular cells to recruit NF-kB and AP-1 to C3 and Cfb, coordinately inducing complement component 3 (C3) and Factor B (FB). Cytoplasmic FB drives cleavage-activation of cell-intrinsic C3, which supports tubular cell mitochondrial metabolic adaptation to stress and accumulation of C3aR-expressing macrophages around injured tubules. Nuclear FB, on the other hand, binds chromatin through a previously unrecognized DNA-binding interface and mediates histone H3 proteolysis and the preferential remodeling of chromatin promotors enriched in transcriptional programs relevant to maladaptive repair. Key features of this injury-associated C3-FB response, including intranuclear FB, are conserved in human kidney disease, associate with kidney dysfunction, and distinguish diseased from healthy kidneys. Together, these findings suggest that extracellular complement-targeting therapies may miss disease-relevant intracellular functions and suggest nuclear FB as a distinct target whose chromatin interaction and processing capacity could selectively limit maladaptive tissue responses beyond conventional inhibition.
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BibTeX
@misc{freiwald2026intracellular,
title = {{Intracellular complement Factor B couples inflammatory sensing to metabolism, chromatin regulation and maladaptive tissue repair}},
author = {T. Freiwald and D. Chauss and M. Tajmul and J. L. Trujillo-Ochoa and D. Kumar and J. Ma and M. Snyder and N. Cheru and J. F. Jaeger and Y. Zhuang and J. B. Gregor and G. Ganne and L. Wang and Y. Guo and M. Gunkel and T. Huber and T. Wiech and E. E. West and S. Ayyadevara and M. Kolev and S. Briggs and C. Kemper and M. Kazemian and D. Portilla and B. Afzali},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.04.756581},
url = {https://www.biorxiv.org/content/10.64898/2026.10.04.756581v1},
note = {CC0},
}
RIS
TY - UNPB
TI - Intracellular complement Factor B couples inflammatory sensing to metabolism, chromatin regulation and maladaptive tissue repair
AU - T. Freiwald
AU - D. Chauss
AU - M. Tajmul
AU - J. L. Trujillo-Ochoa
AU - D. Kumar
AU - J. Ma
AU - M. Snyder
AU - N. Cheru
AU - J. F. Jaeger
AU - Y. Zhuang
AU - J. B. Gregor
AU - G. Ganne
AU - L. Wang
AU - Y. Guo
AU - M. Gunkel
AU - T. Huber
AU - T. Wiech
AU - E. E. West
AU - S. Ayyadevara
AU - M. Kolev
AU - S. Briggs
AU - C. Kemper
AU - M. Kazemian
AU - D. Portilla
AU - B. Afzali
PY - 2026
DA - 2026/10/04
PB - bioRxiv
DO - 10.64898/2026.10.04.756581
UR - https://www.biorxiv.org/content/10.64898/2026.10.04.756581v1
AB - Inflammatory signals are broadly conserved, yet how tissue context converts them into programs of recovery or maladaptive repair remains unclear. Using kidney injury as a model of inflammation-to-repair transitions, we identify an injury-induced proximal-tubule complement program in which cell-intrinsic complement proteins are repurposed across subcellular compartments to couple inflammation to metabolic and chromatin regulation and promote maladaptive fibrotic remodeling. Mechanistically, myeloid-derived IL-1b; signals through IL-1R1 on injured tubular cells to recruit NF-kB and AP-1 to C3 and Cfb, coordinately inducing complement component 3 (C3) and Factor B (FB). Cytoplasmic FB drives cleavage-activation of cell-intrinsic C3, which supports tubular cell mitochondrial metabolic adaptation to stress and accumulation of C3aR-expressing macrophages around injured tubules. Nuclear FB, on the other hand, binds chromatin through a previously unrecognized DNA-binding interface and mediates histone H3 proteolysis and the preferential remodeling of chromatin promotors enriched in transcriptional programs relevant to maladaptive repair. Key features of this injury-associated C3-FB response, including intranuclear FB, are conserved in human kidney disease, associate with kidney dysfunction, and distinguish diseased from healthy kidneys. Together, these findings suggest that extracellular complement-targeting therapies may miss disease-relevant intracellular functions and suggest nuclear FB as a distinct target whose chromatin interaction and processing capacity could selectively limit maladaptive tissue responses beyond conventional inhibition.
ER -