{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T01:49:51Z","timestamp":1792547391436,"version":"4.5.0"},"reference-count":42,"publisher":"Wiley","issue":"11","license":[{"start":{"date-parts":[[2015,10,28]],"date-time":"2015-10-28T00:00:00Z","timestamp":1445990400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/501100001700","name":"Ministry of Education, Culture, Sports, Science, and Technology of Japan","doi-asserted-by":"crossref","award":["26461436"],"award-info":[{"award-number":["26461436"]}],"id":[{"id":"10.13039\/501100001700","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001700","name":"Ministry of Education, Culture, Sports, Science, and Technology of Japan","doi-asserted-by":"crossref","award":["23591404"],"award-info":[{"award-number":["23591404"]}],"id":[{"id":"10.13039\/501100001700","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Arthritis &amp; Rheumatology"],"published-print":{"date-parts":[[2015,11]]},"abstract":"<jats:sec><jats:title>Objective<\/jats:title><jats:p>Synovial fluid pH is decreased in patients with rheumatoid arthritis (RA); however, the underlying mechanisms are unclear. We undertook this study to examine the mechanism by which synovial fluid pH is regulated and to explore the possibility of a therapeutic strategy by manipulating this mechanism.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We determined the pH and lactate concentration in synovial fluid from 16 RA patients. Cultured synovial fibroblasts (SFs) from the inflamed joints of 9 RA patients (RASFs) were examined for the expression of ion transporters that regulate intracellular and extracellular pH. The ion transporter up\u2010regulated in RASF lines was then suppressed in RASFs by small interfering RNA (siRNA), and the effect of transfection on viability and proliferation was investigated. Finally, we examined the therapeutic effect of electrotransfer of monocarboxylate transporter 4 (MCT4)\u2013specific siRNA into the articular synovium of mice with collagen\u2010induced arthritis (CIA).<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Synovial fluid pH correlated inversely with both the Disease Activity Score in 28 joints using the C\u2010reactive protein level and the synovial fluid lactate levels. RASFs exhibited up\u2010regulated transcription of MCT4 messenger RNA. MCT4 exported intracellular lactate into the extracellular space. RASFs had significantly higher MCT4 protein levels than did SFs from patients with osteoarthritis. Knockdown of MCT4 induced intrinsic apoptosis of RASFs, thereby inhibiting their proliferation. Moreover, electrotransfer of MCT4\u2010specific siRNA into the articular synovium of mice with CIA significantly reduced the severity of arthritis.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>RA activity correlated with decreased synovial fluid pH. This may be due to increased MCT4 expression in RASFs. Silencing MCT4 induced apoptosis in RASFs and reduced the severity of CIA, suggesting that MCT4 is a potential therapeutic target for inflammatory arthritis.<\/jats:p><\/jats:sec>","DOI":"10.1002\/art.39270","type":"journal-article","created":{"date-parts":[[2015,7,26]],"date-time":"2015-07-26T17:16:58Z","timestamp":1437931018000},"page":"2888-2896","source":"Crossref","is-referenced-by-count":63,"title":["Monocarboxylate Transporter 4, Associated With the Acidification of Synovial Fluid, Is a Novel Therapeutic Target for Inflammatory Arthritis"],"prefix":"10.1002","volume":"67","author":[{"given":"Wataru","family":"Fujii","sequence":"first","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yutaka","family":"Kawahito","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hidetake","family":"Nagahara","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuji","family":"Kukida","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takahiro","family":"Seno","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aihiro","family":"Yamamoto","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masataka","family":"Kohno","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryo","family":"Oda","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daigo","family":"Taniguchi","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hiroyoshi","family":"Fujiwara","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Akika","family":"Ejima","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tsunao","family":"Kishida","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Osam","family":"Mazda","sequence":"additional","affiliation":[{"name":"Kyoto Prefectural University of Medicine Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eishi","family":"Ashihara","sequence":"additional","affiliation":[{"name":"Kyoto Pharmaceutical University Kyoto Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2015,10,28]]},"reference":[{"key":"e_1_2_7_2_1","doi-asserted-by":"publisher","DOI":"10.1038\/ncprheum0047"},{"key":"e_1_2_7_3_1","first-page":"775","article-title":"Treat to target in rheumatoid arthritis: fact, fiction, or hypothesis? 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