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Monocarboxylate transporter 4, associated with the acidification of synovial fluid, is a novel therapeutic target for inflammatory arthritis.
Arthritis Rheumatol 2015; 67(11):2888-96AR

Abstract

OBJECTIVE

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.

METHODS

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-regulated 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)-specific siRNA into the articular synovium of mice with collagen-induced arthritis (CIA).

RESULTS

Synovial fluid pH correlated inversely with both the Disease Activity Score in 28 joints using the C-reactive protein level and the synovial fluid lactate levels. RASFs exhibited up-regulated 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-specific siRNA into the articular synovium of mice with CIA significantly reduced the severity of arthritis.

CONCLUSION

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.

Authors+Show Affiliations

Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Prefectural University of Medicine, Kyoto, Japan.Kyoto Pharmaceutical University, Kyoto, Japan.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

26213210

Citation

Fujii, Wataru, et al. "Monocarboxylate Transporter 4, Associated With the Acidification of Synovial Fluid, Is a Novel Therapeutic Target for Inflammatory Arthritis." Arthritis & Rheumatology (Hoboken, N.J.), vol. 67, no. 11, 2015, pp. 2888-96.
Fujii W, Kawahito Y, Nagahara H, et al. Monocarboxylate transporter 4, associated with the acidification of synovial fluid, is a novel therapeutic target for inflammatory arthritis. Arthritis & rheumatology (Hoboken, N.J.). 2015;67(11):2888-96.
Fujii, W., Kawahito, Y., Nagahara, H., Kukida, Y., Seno, T., Yamamoto, A., ... Ashihara, E. (2015). Monocarboxylate transporter 4, associated with the acidification of synovial fluid, is a novel therapeutic target for inflammatory arthritis. Arthritis & Rheumatology (Hoboken, N.J.), 67(11), pp. 2888-96. doi:10.1002/art.39270.
Fujii W, et al. Monocarboxylate Transporter 4, Associated With the Acidification of Synovial Fluid, Is a Novel Therapeutic Target for Inflammatory Arthritis. Arthritis & rheumatology (Hoboken, N.J.). 2015;67(11):2888-96. PubMed PMID: 26213210.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Monocarboxylate transporter 4, associated with the acidification of synovial fluid, is a novel therapeutic target for inflammatory arthritis. AU - Fujii,Wataru, AU - Kawahito,Yutaka, AU - Nagahara,Hidetake, AU - Kukida,Yuji, AU - Seno,Takahiro, AU - Yamamoto,Aihiro, AU - Kohno,Masataka, AU - Oda,Ryo, AU - Taniguchi,Daigo, AU - Fujiwara,Hiroyoshi, AU - Ejima,Akika, AU - Kishida,Tsunao, AU - Mazda,Osam, AU - Ashihara,Eishi, PY - 2014/12/19/received PY - 2015/06/30/accepted PY - 2015/7/28/entrez PY - 2015/7/28/pubmed PY - 2016/2/3/medline SP - 2888 EP - 96 JF - Arthritis & rheumatology (Hoboken, N.J.) VL - 67 IS - 11 N2 - OBJECTIVE: 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. METHODS: 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-regulated 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)-specific siRNA into the articular synovium of mice with collagen-induced arthritis (CIA). RESULTS: Synovial fluid pH correlated inversely with both the Disease Activity Score in 28 joints using the C-reactive protein level and the synovial fluid lactate levels. RASFs exhibited up-regulated 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-specific siRNA into the articular synovium of mice with CIA significantly reduced the severity of arthritis. CONCLUSION: 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. SN - 2326-5205 UR - https://www.unboundmedicine.com/medline/citation/26213210/Monocarboxylate_transporter_4_associated_with_the_acidification_of_synovial_fluid_is_a_novel_therapeutic_target_for_inflammatory_arthritis_ L2 - https://doi.org/10.1002/art.39270 DB - PRIME DP - Unbound Medicine ER -