Hif-1α Knockdown Reduces Glycolytic Metabolism and Induces Cell Death of Human Synovial Fibroblasts Under Normoxic Conditions.

Increased glycolysis and HIF-1α activity are characteristics of cells under hypoxic or inflammatory conditions. Besides, in normal O2 environments, elevated rates of glycolysis support critical cellular mechanisms such as cell survival. The purpose of this study was to analyze the contribution of HIF-1α to the energy metabolism and survival of human synovial fibroblasts (SF) under normoxic conditions. HIF-1α was silenced using lentiviral vectors or small-interfering RNA (siRNA) duplexes. Expression analysis by qRT-PCR and western blot of known HIF-1α target genes in hypoxia demonstrated the presence of functional HIF-1α in normoxic SF and confirmed the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a HIF-1α target even in normoxia. HIF-1α silencing induced apoptotic cell death in cultured SF and, similarly, treatment with glycolytic, but not with OXPHOS inhibitors, induced SF death. Finally, in vivo HIF-1α targeting by siRNA showed a significant reduction in the viability of human SF engrafted into a murine air pouch. Our results demonstrate that SF are highly dependent on glycolytic metabolism and that HIF-1α plays a regulatory role in glycolysis even under aerobic conditions. Local targeting of HIF-1α provides a feasible strategy to reduce SF hyperplasia in chronic arthritic diseases.

Therapeutic effect of the immunomodulatory drug lenalidomide, but not pomalidomide, in experimental models of rheumatoid arthritis and inflammatory bowel disease.

Thalidomide is an immunomodulatory drug (IMiD) with proven therapeutic action in several autoimmune/inflammatory diseases; however, its inherent high toxicity has led to the development of more powerful and safer thalidomide analogs, including lenalidomide and pomalidomide. These are new generation IMiDs that exhibit direct antitumor activity as well as anti-inflammatory/immunomodulatory properties, and are FDA-approved for the treatment of several hematological malignances. Here we investigated the potential therapeutic effects of lenalidomide and pomalidomide in several experimental murine models of autoimmune/inflammatory diseases: 2,4,6-trinitrobenzene sulfonic acid- and dextran sulfate sodium-induced inflammatory bowel disease and type II collagen-induced arthritis. Lenalidomide displayed a strong therapeutic effect in all these models of autoimmune/inflammatory diseases, while the effect of pomalidomide was less pronounced. In vitro experiments confirmed the immunosuppressive effect of both IMiDs on the proliferative response of stimulated human lymphocytes and on the balance of secreted cytokines toward an anti-inflammatory profile. We conclude that lenalidomide may offer a therapeutic opportunity against autoimmune/inflammatory diseases.

TGF-ß antagonist attenuates fibrosis but not luminal narrowing in experimental tracheal stenosis.

OBJECTIVE: Acquired tracheal stenosis (ATS) is an unusual disease often secondary to prolonged mechanical trauma. Acquired tracheal stenosis pathogenesis involves inflammation and subsequent fibrosis with narrowing of the tracheal lumen. Transforming growth factor-ß1 (TGF-ß) represents a pivotal factor in most fibrotic processes, and therefore a potential target in this context. The aim of this study is to analyze the role of TGF-ß as a target for anti-fibrotic interventions in tracheal stenosis. METHODS: Human stenotic tracheobronchial tissues from patients with benign airway stenosis and normal controls from pneumonectomy specimens were analyzed. Tracheal stenosis was induced in adult NZ rabbits by a circumferential thermal injury to the mucosa during open surgery and re-anastomosis. Rabbits were treated postoperatively with a peritracheal collagen sponge containing a TGF-ß peptide antagonist (p17) or vehicle. Fibrosis was determined by Masson's trichrome staining, and smooth muscle cell α-actin+ (α-SMA+ Confirm accuracy.) myofibroblasts, connective tissue growth factor (CTGF), and p-Smad2/3 expression by immunohistochemistry. RESULTS: Human and rabbit stenotic tissues showed extensive submucosal fibrosis, characterized by significantly increased α-SMA+ myofibroblasts and CTGF expression. In human stenotic lesions, increased p-Smad2/3+ nuclei were also observed. p17 treatment significantly reduced the fibrotic thickness, as well as the density of α-SMA+ myofibroblasts and CTGF+ cells in rabbit stenotic lesions, but failed to improve the luminal area. CONCLUSION: ATS is characterized by a TGF-ß dependent fibrotic process, but reduction of the fibrotic component by TGF-ß1 antagonist therapy was not sufficient to improve tracheal narrowing, suggesting that fibrosis may not be the main contributor to luminal stenosis. LEVEL OF EVIDENCE: NA. Laryngoscope, 127:561-567, 2017.

Ectopic lymphoid neogenesis is strongly associated with activation of the IL-23 pathway in rheumatoid synovitis.

INTRODUCTION: The functional relevance of synovial ectopic lymphoid neogenesis (ELN) in rheumatoid arthritis (RA) remains unknown. As ELN correlates with the degree of tissue inflammation, we investigated whether ELN was associated with specific cytokine profiles. METHODS: Synovial ELN was determined by immunohistology and long CD21 isoform (CD21L) expression. Cytokine expression was determined by multiplex enzyme-linked immunosorbent assay (ELISA) and quantitative polymerase chain reaction (PCR) as well as immunohistology in synovial fluid (SF) (n = 44) and tissue (ST) (n = 108), respectively. Production of ELN-associated chemokines by fibroblast-like synoviocytes (FLS) was studied in vitro. RESULTS: Screening analysis of SF by multiplex ELISA showed higher protein levels of interleukin (IL)-23 (p = 0.018) and IL-17F (p = 0.028) in ELN+ versus ELN- samples. Other cytokines, including IL-17A, IL-6, and tumor necrosis factor (TNF)-α, were not different. The association between IL-23 and ELN was not biased by disease activity or other clinical features and was confirmed by higher IL-23 mRNA expression in ELN+ versus ELN- ST samples (p = 0.030), a correlation between IL-23 and CD21L expression in the same samples (r = 0.70 p < 0.0001), and a similar correlation in two independent ST sample sets (r = 0.778 p < 0.0001 and r = 0.817 p = 0.011). IL-23 p19 staining was neither restricted nor enhanced in close proximity of ectopic lymphoid follicles, and neither IL-23 nor IL-17A stimulation induced expression of the ELN-associated CC chemokine ligand, CCL21 and CXC chemokine ligand CXCL13, by FLS. Downstream of IL-23, CD21L expression was significantly associated with IL-17F, IL-21, and IL-22, but not IL-17A in two independent ST sample sets. CONCLUSIONS: Synovial ELN in RA is strongly associated with activation of the IL-23 pathway but not with IL-17A.