Interferon-γ Released by Activated CD8+ T Lymphocytes Impairs the Calcium Resorption Potential of Osteoclasts in Calcified Human Aortic Valves

• DOI: 10.1016/j.ajpath.2017.02.012
• Publication Date: 2017-04-19T02:00:19Z
• Authors: Edit Nagy; Yang Lei; Eduardo Martínez-...; Simon C. Body; Florian Schlotter; Michael Creager; Alexander Assmann; Kamal Khabbaz; Peter Libby; Göran K. Hansson; Elena Aikawa
• Keywords: Aged, 80 and over; Heart Valve Prosthesis Implantation; Male; RANK Ligand; Calcinosis; Osteoclasts; Aortic Valve Stenosis; CD8-Positive T-Lymphocytes; Middle Aged; Lymphocyte Activation; Tissue Culture Techniques; Interferon-gamma; 03 medical and health sciences; 0302 clinical medicine; Gene Expression Regulation; Aortic Valve; Humans; Calcium; Female; Aged

In calcific aortic valve disease (CAVD), activated T lymphocytes localize with osteoclast regions; however, the functional consequences of this association remain unknown. We hypothesized that CD8+ T cells modulate calcification in CAVD. CAVD valves (n = 52) dissected into noncalcified and calcified portions were subjected to mRNA extraction, real-time quantitative PCR, enzyme-linked immunosorbent assay, and immunohistochemical analyses. Compared with noncalcified portions, calcified regions exhibited elevated transcripts for CD8, interferon (IFN)-γ, CXCL9, Perforin 1, Granzyme B, and heat shock protein 60. Osteoclast-associated receptor activator of NK-κB ligand (RANKL), tartrate-resistant acid phosphatase (TRAP), and osteoclast-associated receptor increased significantly. The stimulation of tissue with phorbol-12-myristate-13-acetate and ionomycin, recapitulating CAVD microenvironment, resulted in IFN-γ release. Real-time quantitative PCR detected mRNAs for CD8+ T-cell activation (Perforin 1, Granzyme B). In stimulated versus unstimulated organoid cultures, elevated IFN-γ reduced the mRNAs encoding for RANKL, TRAP, and Cathepsin K. Molecular imaging showed increased calcium signal intensity in stimulated versus unstimulated parts. CD14+ monocytes treated either with recombinant human IFN-γ or with conditioned media-derived IFN-γ exhibited low levels of Cathepsin K, TRAP, RANK, and tumor necrosis factor receptor-associated factor 6 mRNAs, whereas concentrations of the T-cell co-activators CD80 and CD86 increased in parallel with reduced osteoclast resorptive function, effects abrogated by neutralizing anti-IFN-γ antibodies. CD8+ cell-derived IFN-γ suppresses osteoclast function and may thus favor calcification in CAVD.