Impaired Hard- and Soft-Tissue Socket Healing in Lupus-Prone MRL/lpr Mice

Introduction and aims Systemic lupus erythematosus (SLE) is a chronic autoimmune disease associated with impaired wound healing and increased oral surgical risk. However, whether the autoimmune environment alters the coordinated hard and soft tissue regeneration within the extraction socket remains unknown. We evaluated this question using the MRL/lpr mice and background-matched MRL/MpJ mice. Methods Female MRL/lpr mice and age-matched MRL/MpJ controls (SLE, n = 6 per strain at each time point) underwent right maxillary first molar extraction. Specimens were harvested at days 7, 14 and 28. Hard tissue healing was assessed by micro-computed tomography and histological staining including haematoxylin and eosin, Masson trichrome and tartrate-resistant acid phosphatase. Soft tissue healing was assessed by epithelial morphometry and Picrosirius red staining under polarised light microscopy. Results Compared with MRL/MpJ mice, MRL/lpr mice showed greater vertical alveolar ridge resorption on the buccal and middle aspects at day 28, with reduced bone volume fraction and bone mineral density. Increased numbers of tartrate-resistant acid phosphatase-positive multinucleated cells were spatially restricted to the alveolar crest wall. MRL/lpr mice also showed thinner epithelium, reduced keratinisation, flattened rete pegs, persistent inflammation, greater collagen-fibre dispersion and a lower orange-red-to-green birefringent area ratio at day 28, consistent with delayed collagen-fibre maturation. Conclusion Relative to MRL/MpJ controls, lupus-prone MRL/lpr mice showed impaired extraction socket healing through coupled hard and soft tissue deficits. These preclinical findings still require mechanistic and human validation. Clinical relevance These preclinical findings suggest that careful assessment of socket healing and ridge dimensions may be warranted in patients with SLE, particularly before implant placement. Clinical studies are needed before specific surgical protocols or healing intervals can be recommended.