Pelvic organ prolapse (POP) represents a highly prevalent condition among women, particularly following childbirth and during aging, with recurrence rates following surgical intervention posing significant clinical challenges that substantially increase treatment difficulty and healthcare burden. Despite advances in surgical techniques, the molecular mechanisms underlying POP recurrence remain poorly understood, limiting the development of targeted therapeutic strategies. A research study by Yaqian Li and colleagues employed single-cell RNA sequencing technology to conduct comprehensive comparative analysis of vaginal fibroblasts, smooth muscle cells, and macrophages between recurrent and primary POP patients, revealing substantial molecular heterogeneity that provides novel insights into the cellular and molecular drivers of POP recurrence.
The research utilized publicly available single-cell RNA sequencing datasets to systematically characterize cellular populations within vaginal tissues from control subjects, primary POP patients, and recurrent POP patients. Through rigorous computational analysis of differentially expressed genes (DEGs), the investigators discovered that recurrent and primary POP shared relatively few common DEGs while exhibiting substantially more subtype-specific differentially expressed genes, confirming significant molecular heterogeneity between these two clinical presentations. This finding suggests that recurrent POP may represent a distinct pathological entity rather than simply a continuation of primary disease processes.
Analysis of fibroblast populations revealed particularly informative patterns. Shared fibroblast DEGs in both POP subtypes were primarily enriched in collagen fibril organization pathways, indicating that disruption of normal collagen architecture represents a common feature of POP pathogenesis regardless of recurrence status. However, recurrent POP demonstrated unique upregulation of genes specifically related to collagen metabolism and leukocyte migration, suggesting enhanced tissue remodeling and inflammatory cell recruitment in recurrent cases. Most notably, NKD2+ myofibroblasts were significantly more abundant in recurrent POP compared to primary POP. Myofibroblasts play crucial roles in tissue contractility and extracellular matrix deposition, and their increased presence in recurrent POP may contribute to aberrant tissue stiffening and compromised pelvic floor support function.
Macrophage analysis uncovered both conserved and distinct features between primary and recurrent POP. Shared upregulated DEGs in macrophages from both patient groups were enriched in extracellular matrix remodeling and transforming growth factor-beta (TGF-β) signaling pathways, highlighting the conserved roles of macrophage-fibroblast interactions in POP pathogenesis. TGF-β signaling represents a central regulator of fibrosis and tissue repair, and its activation in both conditions underscores the importance of immune-stromal cell communication in pelvic floor dysfunction. However, certain fibrotic-related genes showed specific upregulation in recurrent POP macrophages, implicating potential distinct fibrotic mechanisms that may drive disease recurrence.
The proportion of M2-like macrophages emerged as a particularly significant distinguishing feature, with recurrent POP showing higher M2-like macrophage proportions compared to primary POP. M2 macrophages typically promote tissue repair, fibrosis, and anti-inflammatory responses. While beneficial for acute wound healing, excessive M2 polarization can drive pathological fibrosis and tissue remodeling that compromises normal anatomical structure and function. The shift toward M2-like macrophage predominance in recurrent POP suggests a pro-fibrotic immune microenvironment that may perpetuate aberrant tissue remodeling following initial surgical repair.
These collective findings reveal a potential shift toward pro-fibrotic and tissue-remodeling immune microenvironment in recurrent POP compared to primary disease. The enhanced collagen metabolism, increased myofibroblast populations, and M2 macrophage polarization observed in recurrent cases suggest that primary surgical intervention may fail to address underlying pathological tissue remodeling processes, leading to recurrence through continued aberrant fibrosis and matrix deposition.
From a mechanistic perspective, the study highlights the importance of chemokine signaling pathways in mediating immune cell recruitment and activation within prolapsed tissues. The observed upregulation of leukocyte migration-related genes in recurrent POP fibroblasts suggests enhanced chemotactic signaling that may perpetuate chronic inflammation and fibrosis. Additionally, the differential Wnt signaling pathway activation observed between conditions may contribute to altered fibroblast activation states and myofibroblast differentiation.
The clinical implications of these findings are substantial. Current surgical approaches for POP focus primarily on anatomical correction without addressing underlying molecular pathologies. The identification of distinct molecular signatures in recurrent POP suggests that adjunctive therapies targeting fibrosis, inflammation, or specific immune cell populations might improve surgical outcomes and reduce recurrence rates. Potential therapeutic strategies could include anti-fibrotic agents, macrophage polarization modulators, or interventions targeting specific chemokine signaling pathways.
Future research directions highlighted by this study include validation of these findings in larger, independent cohorts, functional characterization of specific cell subpopulations identified, and development of targeted therapeutic approaches based on the molecular signatures uncovered. The single-cell transcriptomic approach employed provides a template for similar investigations in other recurrent pelvic floor disorders, potentially transforming understanding of these common and debilitating conditions.
In conclusion, this comprehensive single-cell analysis reveals substantial molecular heterogeneity between recurrent and primary pelvic organ prolapse, characterized by distinct fibroblast activation states, macrophage polarization patterns, and pro-fibrotic signaling pathways. These findings provide crucial insights into the cellular mechanisms driving POP recurrence and establish a foundation for developing novel targeted therapeutic strategies to improve patient outcomes.
