Iron overload causes macrophages to produce a pro-inflammatory phenotype in the synovium of hemophiliac arthritis via the acetyl-p53 pathway.

AIM: Haemophiliac arthritis (HA) is caused by spontaneous intra-articular hemorrhage and repeated intra-articular hematomas, leading to iron overload, which, in turn, induces M1 macrophage polarisation and inflammatory cytokine secretion, resulting in synovitis. Here, we explored the mechanism by which iron overload in HA induces the polarisation of M1 macrophages, providing a new approach for the treatment of HA synovitis. METHODS: The synovium from the knee joints of normal amputees and patients with HA was collected. Pathological changes in the synovial tissues were analysed using hematoxylin and eosin staining. Iron tissue deposition was evaluated using the iron assay kit and Prussia Blue staining, while macrophage phenotype was determined using immunofluorescence. The levels of pro-inflammatory cytokines and p53 acetylation were determine using western blotting. An in vitro iron overload model was established by inducing THP-1 macrophages with ferric ammonium citrate, and the involvement of acetylated p53 in M1 macrophage polarisation was investigated. RESULTS: Compared to control samples, the iron content in the synovium of patients with HA was significantly increased. The protein levels of M1 macrophage markers, pro-inflammatory cytokines, and acetylated p53, were also significantly elevated in the synovial tissues of patients with HA. Similar results were observed in the in vitro iron overload model. Furthermore, the inhibition of p53 acetylation in vitro reversed these iron overload-induced effects. CONCLUSION: In patients with HA, iron overload induced synovial p53 acetylation, leading to macrophage polarisation toward the M1 phenotype and increased inflammatory cytokine secretion, resulting in synovitis. HIGHLIGHTS: Synovial iron overload is associated with changes in P53 acetylation in hemophiliac arthritis (HA). Acetylated p53, a known regulator of macrophage polarization, is highly expressed in HA synovium, suggesting a potential role in M1 polarization. HA synovial macrophages predominantly polarize into the pro-inflammatory M1 phenotype, secreting elevated levels of pro-inflammatory cytokines.

Postural control during a transition task in haemophilic children, adolescents and young adults with haemophilic ankle arthropathy.

BACKGROUND: The aim of this study was to determine whether young haemophilic boys with and without MRI-based signs of ankle arthropathy demonstrate reduced balance ability during a transition task with eyes open and eyes closed. METHODS: Thirty-four haemophilic bodies and 28 typically developing boys aged 6-20 years participated to this study. Structural integrity of the tarsal foot joints of all haemophilic boys was assessed with MRI. All participants performed a standard transition task from double-leg stance to single-leg stance with eyes open and eyes closed. Comparison of balance features derived from the centre of pressure displacement captured by a single force platform was performed between the different haemophilia subgroups and sex-age-height matched peers. FINDINGS: The haemophilic boys without signs of arthropathy presented only a higher intermediate phase velocity during the eyes closed condition (P = .05). The haemophilic boys with signs of arthropathy had significantly higher displacement after the time to new stability point, and 95% Ellipse Sway Area and Balance Area compared to their matched peers during eyes open test (P < .05). Similar findings were observed during the eyes closed test for the displacement after the time to new stability point and 95% Ellipse Sway Area (P < .05). No significant differences were observed between affected and non-affected side of the unilateral affected patients. INTERPRETATION: We suggest that the pathophysiological cascade associated with chronic bleeding episodes should not be considered as a "simple" musculoskeletal injury, hence more as a complex neurophysiological dysfunction which may originate both from unilateral and bilateral deterioration of the musculoskeletal system.