AB0167 Metformin has anti-inflammatory potential by reducing p-gp expression on pbmcs of patients with lupus
Authors: S. Kansurkar, M.K. Rai, D.P. Misra, V. Agarwal
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Metformin causes immunomodulation by activation of AMP-kinase and thereby inhibition of mTOR pathway. Metformin reduces disease activity in lupus mouse models.<sup>1</sup> A study has shown that its use in lupus patients decreased corticosteroid dose and prevented flares.<sup>2</sup> P-glycoprotein expression is linked to drug resistance and increased cytokine production. Metformin inhibits expression of P- Glycoprotein (P-gp) in cancer cells.<sup>3</sup> There is scarce data on effect of metformin on P-gp expression and cytokine secretion on immune cells in autoimmune diseases like lupus. <h3>Objectives</h3> To study the effect of metformin on P-gp expression in PBMCs of lupus patients and its effect on inflammatory cytokines secretion. To determine optimum concentration required for such an effect. <h3>Methods</h3> PBMCs of nine lupus patients(Mean age 30 yrs, all females) were cultured using RPMA medium and then stimulated with PMA/ ionomycin, with or without increasing dose of metformin (0.01, 0.1,1,10 mMol/L) for 24 h. Cytokines IL-1b, IL-6, IFN-g and IL-10 were analyzed by ELISA in culture supernatant. Cell viability was independently assessed by MTT assay. P-gp expression was measured in same samples by flow-cytometry. <h3>Results</h3> In MTT assay viability of cells was maintained across all concentrations of metformin used in this study(figure 1a). Metformin decreased expression of P-gp in PBMCs in dose dependent manner (p=0.003). (figure 1b). In the PBMC cultures with PMA and increasing concentration of metformin, there was decrease in production of pro-inflammatory cytokines: IL-1b (p=0.001), IL-6 (p=0.007) and IFNg (p&lt;0.001) at even the lowest concentration of metformin. There was increase in production of anti-inflammatory cytokine IL-10 (p=0.014). The suppression of IL-1, IL-6, IFNg and increase in IL10 production was dose dependent. <h3>Conclusions</h3> Metformin inhibits P-gp expression which is responsible for resistance to action of various drugs including corticosteroids which are cornerstones of treatment in SLE. Metformin thus may help to reduce corticosteroid dose. Anti-inflammatory activity seen in this study is occurring at concentrations which are therapeutically achievable. Plasma levels of metformin at the therapeutic doses commonly used for diabetes are usually around 0.01–0.04 mM/L.<sup>4</sup> Present study has demonstrated anti-inflammatory effect of metformin at this concentration. Metformin offers dual advantage which has anti-inflammatory activity and also has a potential to reduce drug resistance to other therapeutic agents. <h3>References</h3> [1] Lee S-Y, Moon S-J, Kim E-K, et al. Metformin Suppresses Systemic Autoimmunity in Roquin<i>san/san</i> Mice through Inhibiting B Cell Differentiation into Plasma Cells via Regulation of AMPK/mTOR/STAT3. The Journal of Immunology Author Choice 2017;198(7):2661–2670. [2] Yin Y, Choi SC, Xu Z, Perry DJ, Seay H, Croker BP, et al. Normalization of CD4+ T cell metabolism reverses lupus. Sci Transl Med 2015. [3] Kim HG, Hien TT, Han EH, Hwang YP, Choi JH, Kang KW, et al. Metformin inhibits P-glycoprotein expression via the NF-kappaB pathway and CRE transcriptional activity through AMPK activation. British journal of pharmacology. 2011;162(5):1096–108. [4] Ling He, Fredric E. Wondisford, Metformin Action: Concentrations Matter, Cell Metabolism 2015;21(2):159–162. <h3>Acknowledgements</h3> Thanks to Swati Chouhan, Abhishek, Sakir, Rutviz, Suvrat, Pravin, Sonia for their immense help. <h3>Disclosure of Interest</h3> None declared