Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose
AMP-activated protein kinase (AMPK) is a highly conserved, regulator of cellular energy status. In inflammation, AMPK inactivation is associated with increased glucose consumption through aerobic glycolysis, and up-regulation of pro-inflammatory effector responses. Pseudostarvation of cells through AMPK activation by hypoglycaemic therapy reverses these effects through downregulation of pro-inflammatory transcription factors, including NFκB/HIF-1α. Here we demonstrate AMPK upregulation in RA synovial tissues (RAST) after successful treatment, and inhibition of pro-inflammatory responses following pharmacological AMPK activation by metformin/phenformin in vitro.
Methods
RAST from RA patients during arthroscopy pre and 3/12 post treatment with anti-TNF therapy, were stained by immunohistochemistry for activated AMPK (pAMPK) and inactive AMPK (AMPK). Primary Human Microvascular Endothelial Cells (HMVEC) and K4 Synovial fibroblasts (K4 SF) were stimulated with LPS/TNFα (10ng/ml) in the presence of AMPK activators metformin/phenformin (0.5–2 mM). Culture supernatants were evaluated for IL-6 and IL-8 by ELISA. pAMPK and AMPK expression in K4 SF protein lysates were analysed by Immunoblotting normalized against β-actin.
Results
pAMPK was differentially expressed with low expression in highly inflamed RAST pre-treatment, and high expression post-treatment, in concert with a reduction in clinical disease activity.
In LPS and TNFα stimulated K4 SF, IL-6 and IL-8 production is decreased in the presence of metformin and phenformin in a dose dependent manner, with phenformin the more potent effect (P < 0.0001).
In LPS stimulated HMVEC, the production of IL-6 was also decreased in the presence of metformin or phenformin, dose dependent manner, with phenformin the more potent; 2428pg/ml (LPS) reduced to 2263pg/ml (Metformin 0.5mM), 149pg/ml (Metformin 1mM, P=0.0005), 1387 (Metformin 2mM, P<0.0001); 917pg/ml (Phenformin 0.5mM, P<0.0001), 629pg/ml (Phenformin 1mM, P <0.0001) and 306pg/ml (Phenformin 2mM, P<0.0001). Decreased production of IL-8 was seen with phenformin; 12572pg/ml (LPS) reduced to 8270pg/ml (0.5mM, P<0.0001), 5731pg/ml (1mM, P<0.0001) and 409pg/ml (2mM, P<0.0001). IL-8 production was not decreased in LPS stimulated cells in the presence of Metformin.
By immunoblot, pAMPK expression was strongly upregulated in the presence of metformin or phenformin (2mM) compared to unstimulated K4 SF cells indicating a role of both drugs in activating AMPK.
Conclusion
AMPK activation is associated with reduced RA disease activity and down-regulation of pro-inflammatory effector responses. AMPK activating drugs, such as Metformin, may be suitable as an additional therapeutic agent in the treatment of RA.
Disclosure:
L. Gallagher,
None;
U. Fearon,
None;
D. J. Veale,
Abbvie,
2,
MSD,
2,
Pfizer Inc,
2,
Roche ,
2,
Pfizer ,
5,
Roche ,
5,
Abbott,
8,
MSD,
8,
Pfizer,
8,
Roche ,
8;
D. Kane,
None;
L. A. O’Neill,
None;
R. Mullan,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/pseudostarvation-by-ampk-activator-therapy-is-associated-with-reduced-disease-activity-and-downregulation-of-pro-inflammatory-responses-in-rheumatoid-arthritis-ra/