Transcriptome landscape of the late-stage alcohol-induced osteonecrosis of the human femoral head.

Osteonecrosis resulting from heavy ethanol consumption is one of the major causes of nontraumatic osteonecrosis of the femoral head (ONFH). The underlying pathological and molecular mechanisms remain elusive. In this study, we performed deep RNA sequencing from femoral heads of patients diagnosed with late-stage alcohol-induced ONFH (AIONFH), other types of ONFH and traumatic injury (bone fracture). Genome-wide gene expression analyses identified 690 differentially expressed mRNAs in AIONFH. Gene annotation and pathway analyses revealed significant dysregulated genes involved in hemostasis, angiogenesis and bone remodeling processes from the late-stage AIONFH. Notably, ADH1B, which codes for one of the major alcohol dehydrogenases, is significantly upregulated in AIONFH samples. Further, we found that the ADH1B protein was primarily expressed in smooth muscle cells of the blood vessels, stromal cells and adipocytes of the femoral heads of AIONFH patients; but was absent in other ONFH samples. Our analyses also revealed unique long non-coding RNA (lncRNA) expression profiles and identified novel lncRNAs in AIONFH. In addition, we observed a close co-expression correlation between lncRNAs and mRNAs in AIONFH suggesting that cis-gene regulation represents a major mechanism of action of human femoral lncRNAs. Further, the expression signature of lncRNAs, but not mRNAs, distinguishes AIONFH from other types of ONFH. Taken together, our studies uncovered novel molecular signatures associated with late-stage AIONFH in which the dysregulation of several key signaling pathways within the femoral head may be involved in AIONFH. Subsequently, lncRNAs may serve as potential biomarkers for diagnosis and therapeutic treatment of AIONFH. Further studies are needed to confirm that ADH1B is specifically upregulated in AIONFH and not generally upregulated in patients who consume alcohol excessively.