IL-1β inhibition in stabilizing atherosclerotic plaques: The critical role of fibroblast-like cells.

Targeting interleukin-1 beta (IL-1β) to mitigate inflammation is known to stabilize atherosclerotic plaques, thereby lowering the risk of acute cardiovascular events. The precise mechanisms are not yet known. Fideler et al. examined the effects of IL-1β on exaggerated atherosclerosis following clonal hematopoiesis of indeterminate potential (CHIP). Unexpectedly, they showed an effect of IL-1β blockage on fibroblast-like cells and their role in the progression of atherosclerosis in the presence of CHIP. Here, we discuss these findings and place them in context of current insights on plaque fibroblast identity and function. While single cell sequencing studies had observed the presence of plaque fibroblasts in atherosclerotic plaques, their function has yet to be unraveled. By focusing on both in vitro and ex vivo models, the research explored how IL-1β stimulation drives functional and molecular changes in fibroblast-like cells, such as increased cytokine production and enhanced matrix degradation, which replicate the inflammatory microenvironment commonly seen in atherosclerotic lesions. Furthermore, the study suggests that inhibiting IL-1β might encourage the accumulation of fibroblast-like cells within the fibrous cap, a process that could improve plaque stability by reducing inflammatory activity and strengthening the structural integrity of the plaque. Depletion of proteoglycan 4 (Prg4) -positive cells, that represent fibroblasts amongst other cell types, reduced cap thickness in atherosclerosis with clonal hematopoiesis of indeterminate potential. The findings suggest that IL-1β not only plays a critical role in promoting inflammation, but also in altering the phenotype of fibroblast-like cells, contributing to the destabilization of atherosclerotic plaques. This study is the first to show a function of plaque fibroblast-like cells in exaggerated atherosclerosis following clonal hematopoiesis of indeterminate potential. Future studies should confirm this effect in models without clonal hematopoiesis of indeterminate potential, and with fibroblast depletion based on more specific fibroblast genes.