Distinct fibroblast progenitor subpopulation expedites regenerative mucosal healing by immunomodulation

Abstract

Injuries that heal by fibrosis can compromise organ function and increase patient morbidity. The oral mucosal barrier has a high regenerative capacity with minimal scarring, but the cellular mechanisms remain elusive. Here, we identify distinct postnatal paired-related homeobox-1+ (Prx1+) cells as a critical fibroblast subpopulation that expedites mucosal healing by facilitating early immune response. Using transplantation and genetic ablation model in mice, we show that oral mucosa enriched with Prx1+ cells heals faster than those that lack Prx1+ cells. Lineage tracing and scRNA-seq reveal that Prx1+ fibroblasts exhibit progenitor signatures in physiologic and injured conditions. Mechanistically, Prx1+ progenitors accelerate wound healing by differentiating into immunomodulatory SCA1+ fibroblasts, which prime macrophage recruitment through CCL2 as a key part of pro-wound healing response. Furthermore, human Prx1+ fibroblasts share similar gene and spatial profiles compared to their murine counterpart. Thus, our data suggest that Prx1+ fibroblasts may provide a valuable source in regenerative procedures for the treatment of corneal wounds and enteropathic fibrosis.

Primed inflammatory response by fibroblast subset is necessary for proper oral and cutaneous wound healing

“…(a-j) N = 5-7 per group for a total of 12 mice. Student's t-test, *p < 0.05, **p < 0.01, ***p < 0.001.facilitates a quicker transition to resolution of inflammation (Iglesias-Bartolome et al, 2018;Ko et al, 2023). In this study, we found that the expression of CXCL1 and CCL2 was substantially elevated in Prx1Cre + fibroblasts.…”

“…We examined day 4 wounds, an early time point during which the inflammatory phase is still active (Ko et al., 2023). The immunofluorescence experiment on day 4 oral wound was performed to quantify nuclear NF‐κB expression, indicative of its translocation and activation, in spindle‐shaped vimentin + fibroblasts which were either immunopositive for Prx1 + or not (Figure 2a).…”

“…Animal studies have shown that perturbation of pro‐inflammatory pathways can negatively affect wound healing processes (Sullivan et al., 1999; G. Wang et al., 2021). A unique feature of oral wound healing is subdued inflammation (Guo & Dipietro, 2010), and recent studies have demonstrated that this is a consequence of a marked initial innate immune response that facilitates a quicker transition to resolution of inflammation (Iglesias‐Bartolome et al., 2018; Ko et al., 2023). In this study, we found that the expression of CXCL1 and CCL2 was substantially elevated in Prx1Cre + fibroblasts.…”

“…Growing evidence suggests that fibroblasts represent a heterogeneous pool of mesenchymal cells whose cellular identity is heavily influenced by distinct developmental lineage, mechanical cues, and anatomical niches (Buechler et al., 2021; Junker et al., 2010; Muhl et al., 2020; Plikus et al., 2021). Notably, single‐cell RNA‐sequencing studies of oral mucosal tissues have demonstrated differences in the transcriptomic profile of fibroblast populations, a subset of which was enriched with chemotactic signatures including CXCL1 and CCL2 (Ko et al., 2023; Williams et al., 2021). While these studies highlight the underappreciated role of endogenous fibroblasts in immune modulation for maintaining homeostasis or in facilitating disease progression (S. Davidson et al., 2021; Gauthier et al., 2023), investigating specific inflammatory fibroblast subset has been difficult due to the lack of available in vivo mouse models.…”

Fast and scarless: Prx1+ fibroblasts turbocharge healing

“…In this study, Ko et al (2022) delve into the mechanisms underlying oral regeneration by comparing injury responses in the anterior region of the palate (rugae 2, or R2), which heals rapidly, to posterior palate (R4) wounds that are slow to heal (see figure). In doing so, they identify a unique paired-related homeobox-1 + (Prx1 + ) fibroblast progenitor population in the R2 palate that is missing from the R4 palate.…”