Sex differences in the therapeutic effect of unaltered versus NFκB sensing IL-4 over-expressing mesenchymal stromal cells in a murine model of chronic inflammatory bone loss

Abstract

Wear particles from joint arthroplasties induce chronic inflammation associated with prolonged upregulation of nuclear factor kappa-B (NF-κB) signaling in macrophages and osteoclasts, which leads to osteolysis and implant loosening. Mesenchymal stromal cell (MSC)-based therapy showed great potential for immunomodulation and mitigation of osteolysis in vivo, especially in the chronic phase of inflammation. We previously generated genetically modified MSCs that secrete the anti-inflammatory cytokine interleukin 4 (IL-4) in response to NF-κB activation (NFκB-IL-4 MSCs). However, whether the impact of sexual difference in the internal environment can alter the therapeutic effects of IL-4 over-secreting MSCs that simultaneously mitigate prolonged inflammation and enhance bone formation remains unknown. This study investigated the therapeutic effects of unaltered MSCs versus NFκB-IL-4 MSCs in mitigating chronic inflammation and enhancing bone formation in male and female mice. The murine model was established by continuous infusion of polyethylene particles contaminated with lipopolysaccharide (cPE) into the medullary cavity of the distal femur for 6 weeks to induce chronic inflammation. Unaltered MSCs or NFκB-IL-4 MSCs were infused into the femoral intramedullary cavity in sex-matched groups beginning 3 weeks after primary surgery. Femurs were harvested at 6 weeks, and bone marrow density was measured with micro-computational tomography. Numbers of osteoclast-like cells, osteoblasts, and macrophages were evaluated with histochemical and immunofluorescence staining. cPE infusion resulted in severe bone loss at the surgery site, increased tartrate-resistant acid phosphatase positive osteoclasts and M1 pro-inflammatory macrophages, and decreased alkaline phosphatase expression. MSC-based therapy effectively decreased local bone loss and polarized M1 macrophages into an M2 anti-inflammatory phenotype. In females, unaltered MSCs demonstrated a larger impact in enhancing the osteogenesis, but they demonstrated similar anti-inflammatory effects compared to NFκB-IL-4 MSCs. These results demonstrated that local inflammatory bone loss can be effectively modulated via MSC-based treatments in a sexually dimorphic manner, which could be an efficacious therapeutic strategy for treatment of periprosthetic osteolysis in both genders.

Macrophage Polarization and the Regulation of Bone Immunity in Bone Homeostasis

“…This treatment significantly reduces the number of OCs and effectively decreases local bone loss. 72 In a periodontitis model using diabetic rats, higher levels of macrophage infiltration and M1 macrophage polarization were observed compared to control groups. Additionally, when M1/M2 macrophages were treated with high levels of glucose, the supernatants increased the formation of OCs compared to cells cultured at normal glucose levels.…”

Nano wear particles and the periprosthetic microenvironment in aseptic loosening induced osteolysis following joint arthroplasty

“…Blocking the secretion of the chemokine C-C-motif receptor (CCR1) in MSCs can lead to an increase in particles-induced osteolysis, suggesting that recruiting MSCs to inflamed areas helps limit inflammation and may contribute to bone regeneration ( Gibon et al., 2012 ). Recent studies have also shown that MSCs can increase the ratio of M2/M1 cells, reducing bone resorption and enhancing bone formation ( Shen et al., 2022 ; Kushioka et al., 2023 ). While MSCs primarily regulate adaptive immune responses in inflammatory diseases ( Bernardo and Fibbe, 2013 ), an increasing number of studies indicate their crucial role in modulating innate immunity ( Le Blanc and Mougiakakos, 2012 ).…”

Recent Advances in Mesenchymal Stem Cell-mediated Bone Regeneration

“…It has been investigated that MSCs are activated and polarized in the inflammatory milieu of acute respiratory distress syndrome (ARDS) patients, shifting them toward a proinflammatory phenotype [16]. During bone regeneration or bone repair, the increase of pro-inflammatory cytokines such as IL-1, IL-4, IL-3, IL-6, IL-17a, IL-10, IL-22 and TNF-α leads to instability of the bone microenvironment, which affects the migration, repair, proliferation, and differentiation of MSCs [2,17]. Research evidence have shown that the adhesion and efficacy of MSCs in inflammatory arthritis can be regulated intraarticularly in mouse models, and inflammatory cells have anabolic effects on bone repair by recruiting MSCs and directing their migration and differentiation [18].…”