Rheumatoid arthritis (RA) and osteoarthritis (OA), two common types of arthritis, affect the joints mainly by targeting the synovium and cartilage. Increasing evidence indicates that a significant network connects synovitis and cartilage destruction during the progression of arthritis. We recently demonstrated that hypoxia-inducible factor (HIF)-2alpha causes RA and OA by regulating the expression of catabolic factors in fibroblast-like synoviocytes (FLS) or chondrocytes. To address the reciprocal influences of HIF-2alpha on FLS and chondrocytes, we applied an in vitro co-culture system using a transwell apparatus. When co-cultured with HIF-2alpha-overexpressing chondrocytes, FLS exhibited increased expression of matrix metalloproteinases and inflammatory mediators, similar to the effects induced by tumor-necrosis factor (TNF)-alpha treatment of FLS. Moreover, chondrocytes co-cultured with HIF-2alpha-overexpressing FLS exhibited upregulation of Mmp3 and Mmp13, which is similar to the effects induced by interleukin (IL)-6 treatment of chondrocytes. We confirmed these differential HIF-2alpha-induced effects via distinct secretory mediators using Il6-knockout cells and a TNF-alpha-blocking antibody. The FLS-co-culture-induced gene expression changes in chondrocytes were significantly abrogated by IL-6 deficiency, whereas TNF-alpha neutralization blocked the alterations in gene expression associated with co-culture of FLS with chondrocytes. Our results further suggested that the observed changes might reflect the HIF-2alpha-induced upregulation of specific receptors for TNF-alpha (in FLS) and IL-6 (in chondrocytes). This study broadens our understanding of the possible regulatory mechanisms underlying the crosstalk between the synovium and cartilage in the presence of HIF-2alpha, and may suggest potential new anti-arthritis therapies.
Animals ; Arthritis/genetics/*immunology/pathology ; Arthritis, Rheumatoid/genetics/immunology/pathology ; Basic Helix-Loop-Helix Transcription Factors/genetics/*immunology ; Cells, Cultured ; Chondrocytes/immunology/metabolism/*pathology ; Coculture Techniques ; Fibroblasts/immunology/metabolism/*pathology ; Gene Expression Regulation ; Interleukin-6/genetics/*immunology ; Male ; Mice ; Mice, Inbred C57BL ; Osteoarthritis/genetics/immunology/pathology ; Synovial Membrane/immunology/metabolism/*pathology ; Tumor Necrosis Factor-alpha/genetics/*immunology ; Up-Regulation

OBJECTIVETo study the clinicopathologic features and immunophenotype of renal cell carcinomas, and to discuss their diagnostic value.

METHODSThe clinicopathologic features of 114 cases of renal cell carcinoma were reviewed and categorized on the basis of 2004 WHO classification. Immunohistochemical study for a panel of antibodies (including CK, CD10, vimentin, CD117, AMACR, CK7 and TFE3) was carried out. The follow-up data, if available, were also analyzed.

RESULTSThe cases were reclassified into 5 subtypes, including 77 cases (67.5%) of clear cell carcinoma (CCRCC), 11 cases (9.6%) of papillary renal cell carcinoma (PRCC), 14 cases (12.3%) of chromophobe renal cell carcinoma (chrRCC), 10 cases (8.8%) of renal carcinoma associated with Xp11.2 translocations/TFE3 gene fusions (Xp11.2RCC) and 2 cases (1.8%) of unclassified renal cell carcinoma (unRCC). Immunohistochemical study showed that the expression rates of CK, CD10 and vimentin in CCRCC were 93.5% (72/77), 93.5% (72/77) and 75.3% (58/77), respectively. On the other hand, all the 11 cases of PRCC studied were positive for AMACR. The expression rate of CD117 in chrRCC was 78.5% (11/14). In the 10 cases of Xp11.2 RCC studied, the expression rates of TFE3, AMACR, CD10 and CK were 100% (10/10), 100% (10/10), 90% (9/10) and 70% (7/10), respectively.

CONCLUSIONSThe various subtypes of renal cell carcinomas are heterogeneous in histologic appearance and demonstrate distinctive immunophenotype. The expressions of CD10, vimentin, CD117, AMACR, CK7 and TFE3 are helpful in the differential diagnosis.

Adenocarcinoma, Clear Cell ; pathology ; Adolescent ; Adult ; Aged ; Aged, 80 and over ; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors ; genetics ; immunology ; metabolism ; Biomarkers, Tumor ; analysis ; genetics ; Carcinoma, Papillary ; immunology ; pathology ; Carcinoma, Renal Cell ; immunology ; metabolism ; pathology ; Female ; Gene Fusion ; Humans ; Immunophenotyping ; Kidney Neoplasms ; immunology ; metabolism ; pathology ; Male ; Middle Aged ; Neprilysin ; analysis ; Racemases and Epimerases ; analysis ; genetics ; Translocation, Genetic ; Vimentin ; analysis ; World Health Organization ; Young Adult