Novel susceptibility loci for steroid-associated osteonecrosis of the femoral head in systemic lupus erythematosus

Risk factors and prediction model for osteonecrosis of the femoral head in female systemic lupus erythematosus

Background

Osteonecrosis of the femoral head (ONFH) is a severe complication of systemic lupus erythematosus (SLE) and occurs more frequently in SLE patients than in other autoimmune diseases, which can influence patients' life quality. The objective of this research was to analyze risk factors for the occurrence of ONFH in female SLE patients, construct and validate a risk nomogram model.

Methods

Clinical records of SLE patients who fulfilled the 1997 American College of Rheumatology SLE classification criteria were retrospectively analyzed. The Least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression analysis were used to summarize the independent risk factors of ONFH in female SLE patients, which were used to develop a nomogram. The predictive performance of the nomogram was assessed using the receiver characteristic (ROC) curve, calibration curves and decision curve analysis (DCA).

Results

793 female SLE patients were ultimately included in this study, of which 87 patients (10.9%) developed ONFH. Ten independent risk factors including disease duration, respiratory involvement, menstrual abnormalities, Sjögren's syndrome, osteoporosis, anti-RNP, mycophenolate mofetil, cyclophosphamide, biologics, and the largest daily glucocorticoid (GC) were identified to construct the nomogram. The area under the ROC curve of the nomogram model was 0.826 (95% CI: 0.780-0.872) and its calibration for forecasting the occurrence of ONFH was good (χ2 = 5.589, P = 0.693). DCA showed that the use of nomogram prediction model had certain application in clinical practice when the threshold was 0.05 to 0.95. In subgroup analysis, we found that the risk of ONFH was significantly increased in age at SLE onset of ≤ 50 years old, largest daily GC dose of ≥50 mg and the therapy of GC combined with immunosuppressant patients with menstrual abnormalities.

Conclusion

Menstrual abnormalities were the first time reported for the risk factors of ONFH in female SLE patients, which remind that clinicians should pay more attention on female SLE patients with menstrual abnormalities and take early interventions to prevent or slow the progression of ONFH. Besides, the nomogram prediction model could provide an insightful and applicable tool for physicians to predict the risk of ONFH.

Identification of key genes and pathways associated with gender difference in osteonecrosis of the femoral head based on bioinformatics analysis

OBJECTIVE

To identify different key genes and pathways between males and females by studying differentially expressed genes (DEGs).

METHODS

The gene expression data of GSE123568 were downloaded from GEO database, including osteonecrosis of the femoral head (ONFH) samples from 3 females and 7 males, and DEGs between different gender were identified with R software. Protein-protein interaction (PPI) network was constructed to further analyze the interactions between overlapping DEGs, and finally, GO, KEGG and gene set enrichment analysis (GSEA) were conducted for enrichment analysis.

RESULTS

131 DEGs were identified between ONFH females and ONFH males, including 76 up-regulated genes and 55 down-regulated genes. And 10 hub genes were identified in PPI network, including SLC4A1, GYPA, CXCL8, IFIT1, GBP5, IFI44, IFI44L, IFIT3, KEL and AHSP. Functional enrichment analysis revealed that these genes were mainly enriched in cGMP-PKG signaling pathway, Fatty acid degradation, Non-alcoholic fatty liver disease, Systemic lupus erythematosus, Hematopoietic cell lineage and NO-cGMP-PKG signaling.

CONCLUSIONS

NO-cGMP-PKG signaling may play an important role in the occurrence and development of ONFH. SLC4A1, GYPA, CXCL8, GBP5 and AHSP may be key genes associated with gender difference in the progression of ONFH, which may be ideal targets or prognostic markers for the treatment of ONFH.